Electrochromic mirrors and other electrooptic devices

ABSTRACT

This invention focuses on electrooptic devices and in particular on electrochromic (EC) devices with several aspects directed towards automotive EC mirrors and windows. Adhesive compositions are disclosed herein which improve device processing attributes and their performance and durability.

RELATED APPLICATION/CLAIM OF PRIORITY

This application is a continuation of, and claims priority to U.S.patent application Ser. No. 13/084,430, filed Apr. 11, 2011 which is adivisional of U.S. application Ser. No. 12/781,699, filed on May 10,2010, now U.S. Pat. No. 8,599,466, which is a divisional of U.S.application Ser. No. 11/927,462, filed on Oct. 29, 2007 (now U.S. Pat.No. 7,738,155), which in turn is a divisional of U.S. patent applicationSer. No. 10/793,071, filed on Mar. 4, 2004, (now U.S. Pat. No.7,300,166), each of the above applications (entitled ‘ElectrochromicMirrors and other Electrooptic Devices’) being related to and claimingpriority from each of the following provisional applications:

1. Application Ser. No. 60/452,332 filed on Mar. 5, 2003;

2. Application Ser. No. 60/502,781 filed on Sep. 12, 2003; and

3. Application Ser. No. 60/531,463 filed on Dec. 19, 2003.

The contents of each and all of the foregoing applications areincorporated herein by reference.

TECHNICAL FIELD

This invention is relates to the field of electrooptic (EO) devicesparticularly those EO devices which are electrochromic (EC). Theapplication of these devices are in displays, windows, and variablereflectivity automotive mirrors and mirrors for other applications.

BACKGROUND OF THE INVENTION

Electrochromic devices are being increasingly used for automotivemirrors and have been suggested for many different applications.Recently, several publications suggest use of ionic liquids inelectrolytes for EC devices, e.g. WO 03/003110, U.S. Pat. No. 6,365,301,Japanese application 08-329479 (publication number 10-168028). PublishedUS patent application 20040021928 discloses EC devices using ionicliquids along with preferred characteristics of ionic liquids suitablefor electrooptic devices, and the entire disclosure of that applicationis incorporated herein by reference.

Electrochromic (EC) automotive mirrors and other devices that can befabricated from electrolytes comprising ionic liquids have severaladvantages such as:

-   -   Negligible vapor pressure even at high temperatures    -   Non-flammable

However, the preferred ionic liquids used in this invention have severalother advantages, some of which are:

-   -   High electrochemical stability range    -   Insensitive to moisture absorption    -   Low UV susceptibility    -   Low corrosion

All of these characteristics lead to more durable EC devices.

FIG. 1 shows EC devices where an electrolyte 12 is sandwiched betweentwo conductive, largely parallel substrates. The substrates 10, whichare generally non-conductive, are pre-coated with a conductive material11 on the inward facing surfaces. For windows, both the substrates andthe coatings should be transparent (at least to the eye). Conductivetransparent layers typically are indium tin oxide, fluorine doped tinoxide, etc. For mirrors at least one of these must be transparent. Theother conductor may be a metal layer that also serves as a reflector,otherwise a reflector may be placed on one of the outwardly facingsurface of the substrate. These are called single compartment devices asall electrochemical activity takes place within the electrolytic layer.Both electrochromic (EC) and electroluminescent (EL) devices may be madeusing such a construction. Such constructions are used for EC mirrors(e.g. automotive mirrors) for their self-erasing property, which meansthat the device spontaneously goes to a bleached state when the poweringvoltage is removed. The conductivity of the transparent conductors forautomotive (and other transportation) rear-view mirrors is generallybetween 1 to 100 ohms/square. However, as disclosed in the U.S. patentapplication Ser. No. 10/741,903 filed on Dec. 19, 2003, electrolyteswith higher ionic concentration may use higher resistance transparentconductors as compared to those devices which have lower ionicconcentration. This application (application Ser. No. 10/741,903), whichis incorporated herein by reference, also discloses that for automotivemirror applications, preferred electrolyte thickness is preferably lowerthan 250 microns.

The EC devices may contain other layers deposited on one of theelectrodes. Schematics of such EC devices are shown in FIGS. 2 and 3.FIG. 2 shows the substrates 20 coated with conductive layers 21. Anelectrochemically active layer 23 is deposited on one of the conductivelayers. Examples of such electrochemically active layers are tungstenoxide, Prussian blue, molybdenum oxide, vanadium oxide, polyaniline,polythiophene, and polypyrrole. Such layers may also include derivativesand mixtures of these materials. As an example, a commonly usedderivative of polythiophene is poly-3,4-ethylenedioxythiophene. Thatmaterial is useful in EC mirrors that are intended to have self-erasingproperty. FIG. 2 also shows another kind of EC device where the layer 23changes its electrochromic properties from reflection to transmission.For example, Richardson, T. J. et al (Richardson, T. J., et al, “Lithiumbased EC Mirrors”, Proceedings of the Electrochemical Society, (2003))describe the layer composition as metal hydrides and their alloys,mixtures of magnesium and transition metals, and other metals such ascopper, antimony, bismuth and silver. For example antimony doped withcopper or silver changes reversibly from being reflective to beingtransmissive when reduced with lithium in the electrochemical cell.

FIG. 3 shows a device where each of the substrates 30 is coated withtransparent conductor 31. One transparent conductor is coated with amaterial 33 (as described in Example 2, layer 23), such as tungstenoxide. The tungsten oxide is further coated with an ion-selectivetransportation layer 34 which primarily allows e.g., lithium to gothrough but blocks or retards the motion of the larger ions present inthe electrolyte 32 (see U.S. Pat. No. 6,178,034). The electrolytecomposition is usually the same as in Example 2. This limits the backreaction and increases the memory of the EC device. This construction isuseful for large area windows to conserve power and allow uniformcoloration. These may be used for visors, contrast enhancement filtersfor large displays, automotive and architectural windows.

FIG. 4 shows substrates 40, each coated with a conductive transparentlayer 41. Each conductive transparent layer 41 is further coated withone additional layer (e.g. layer 43 or 45). One of these layers, e.g.,layer 43 has to be electrochromic; the other layer (counterelectrode orthe complimentary layer, CE) may be electrochromic or only store theions reversibly. If the EC layer comprises tungsten oxide and molybdenumoxide, the CE can comprise polyaniline, nickel oxide, iridium oxide andvanadium oxide for electrochromic intercalatable layers. Some examplesof non-electrochromic electrodes are cerium-titanium andvanadium-titanium oxide. Typically these EC devices have good memory andare useful for large area devices.

FIGS. 1 and 2 generally show the schematic structures of EC deviceswhich are being used for commercial mirrors today. All presentlyfabricated commercial automotive EC mirrors have at least one redox dye(e.g. FIG. 2), and most have at least two redox dyes (e.g., FIG. 1) inthe electrolytic medium. In FIG. 1, the electrolytic medium is incontact with the two opposing electronically conductive surfaces of thecell and in FIG. 2 there is a complimentary electrochemically activelayer inserted between one of the electronically conductive surface andthe electrolyte. In both cases at least one of the dyes or theelectrochemically active layer is electrochromic. Electrochromicmaterial is one which reversibly colors when it is either oxidized orreduced by an electric stimulus.

Almost all of the commercial mirror devices are made by backfilling anempty cavity with a liquid electrolyte or a liquid material which laterreacts in-situ to form a solid electrolyte. Backfilling is conductedusing a vacuum apparatus. Since the conventional electrolytic solventshave high vapor pressures, some of these evaporate during theback-filling process and thus contaminate the equipment. The equipmenthas to be cleaned periodically resulting in downtime. Since the ionicliquids have negligible vapor pressure this contamination is reduced forelectrolytes comprising of ionic liquids resulting in a higherefficiency manufacturing process. The ionic liquids maintain negligiblevapor pressure even at elevated temperatures, thus filling at elevatedtemperatures (preferably between 50 to 120° C.) can be carried out tolower the electrolyte viscosity and increase the back-fill rate. Forbackfilling at elevated temperatures the electrolyte and/or the cavityto be filled are pre-heated or heated during the operation.

The disclosure below relates to electrochromic (EC) deviceconfigurations and techniques that are particularly useful in formingautomotive rearview mirrors, and many of which configurations andtechniques are usable for any other application of electrochromic (EC)and other electro optic devices including transmissive type.

One objective of the present invention is to disclose novel reflectiveelectrode compositions for EC mirrors.

Another objective is to disclose novel transparent conductors for ECmirrors.

Yet another objective is to disclose processes to deposit reflectivelayers and transparent conductors for electrochromic mirrors.

Still another objective is to disclose busbar patterns forelectrochromic mirrors.

Yet another objective is to disclose sealant material compositions forelectrochromic assemblies.

Another objective is to disclose integration of displays and indicatorson EC mirrors

Still another objective of this invention is to disclose compositionsfor solid electrolytes for use in electrooptic devices.

Yet another objective is to disclose electronic control circuits forelectrochromic mirrors.

SUMMARY OF INVENTION

The present invention provides new and useful EC devices, particularlyconfigurations that are useful as EC mirrors. The EC mirrors of thisinvention may be fabricated using electrolytes comprising ionic liquidsor conventional solvents.

Moreover the present invention provides new and useful EC deviceconfigurations and techniques for EC mirrors, particularly in regard toforming (a) electrochromic layers, (b) conductive electrodes, (c)reflective layers, (d) transparent conductors, (e) busbar placement (f)displays (h) optical sensors for mirrors and (h) mirrors which colorboth during the day and night.

Still further, the present invention provides new and useful EC deviceconfigurations, techniques and compositions using solid-electrolytes andsealants that, while particularly useful with EC mirrors, haveapplications for other types of EC and electrooptic devices.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: Schematic of a single compartment electrooptic device;

FIG. 2: Schematics of an EC device with an electrochemically activelayer;

FIG. 3: Schematics of an EC device with an electrochemically activelayer covered with an ion selective layer;

FIG. 4: An EC device with an EC layer and a complimentary layer;

FIG. 5a : An EC mirror construction showing a fourth surface reflector;

FIG. 5b : An EC mirror with third surface reflector;

FIG. 5c : An EC mirror with third surface reflector without a tie layer;

FIGS. 6a 6b and 6c : Coating and assembly process of a third surfacemirror and busbar;

FIGS. 7a and 7b : Organic display integrated with an EC device;

FIG. 8: Organic display integrated with an EC device;

FIG. 9: A circuit diagram with an integrated sensor to control an ECmirror;

FIG. 10: A circuit diagram with an integrated sensor to control interiorand exterior EC mirrors;

FIGS. 11a, 11b : Spectrum of an EC device in colored and bleached statesbefore and after cycling;

FIG. 12: A differential scanning calorimeter trace showing the glasstransition temperature (Tg) of an adhesive;

FIG. 13: A viscosity temperature curve of an electrolyte;

FIG. 14: An interior automotive EC mirror construction showing busbarconfiguration for uniformly coloring mirror;

FIG. 15: Schematics of an EC mirror with permanent indicator;

FIG. 16: A schematics for controlling day and night coloring variablereflective mirror system; and

FIG. 17: A schematics of an EC mirror with ASIC controller and opticalfiber inputs.

DETAILED DESCRIPTION OF THE INVENTION

Solid Electrolyte Composition

Background of Electrolyte Composition for EC Devices

Electrolytes for EC devices, particularly for mirrors are generallyliquids. These liquids may be chosen from high boiling point polarliquids, ionic liquids and their mixtures. The use of ionic liquids isnew in many applications, and there are no commercial electroopticproducts utilizing these as electrolytes. Throughout this specificationmore attention will be paid to the use of ionic liquids and shown howthese may be used to easily substitute for conventional solventsresulting in devices with similar and/or improved attributes. However,it should not be construed that this invention is limited in scope onlyto those devices which use ionic liquids in their electrolytes, as manyaspects of this invention are novel for many types of EC and otherelectrooptic devices and applications which may use conventionalsolvents in electrolytes.

Examples of preferred ionic liquids are given in “Room-TemperatureMolten Salts Based on the Quaternary Ammonium Ion,” J. Sun, M. Forsyth,and D. R. MacFarlane, J. Phys. Chem. B, 1998, vol. 102, pages 8858-8864.Most preferred cations for ionic liquids are saturated quaternaryammonium cations. The preferred quaternary ammonium cations for ionicliquid include, but are not limited to, pyridinium, pyrrolidinium,pyridazinium, pyrimidinium, pyrazinium, imidazolium, pyrazolium,thiazolium, oxazolium, and triazolium. These can have varioussubstitutions or substituents, such as H, F, phenyl and alkyl groupswith 1 to 15 carbon atoms. Rings may even be bridged. Preferred anionsare fluorine containing such as triflate (CF₃SO₃ ⁻), imide (N(CF₃SO₂)₂⁻), beti ((C₂F₅SO₂)₂N⁻), methide (CF₃SO₂)₃C⁻), tetraflourob orate (BF₄⁻), hexaflourophosphate (PF₆ ⁻), hexafluoroantimonate (SbF₆ ⁻), C₂H₅SO₄⁻ and hexafluoroarsenate (AsF₆ ⁻). Of these, imide, beti and methideanions are more preferred. An example of a preferred ionic liquid (IL)is 1-Butyl-3-Methyl Pyrrolidinium bis (trifluoromethanesulfonyl)imide(BMP).

Ionic liquids may be used by themselves to form the solvent system forthe electrolytes or conventional solvents (non-ionic) may be added asco-solvents (one or more) for a variety of reasons. Some of the reasonsfor the use as co-solvents with ionic liquids are: viscosity control,change in ionic conductivity, change in freezing point, change in devicekinetics and change in solubility of other added ingredients such asdyes, salts and UV stabilizers. Typically, it is preferred that in thefinished electrolyte the proportion of the ionic liquid to theco-solvents is greater than 1:4 by weight. A more preferred ratio isgreater than 1:2 and the most preferred ratio is greater than 1:1including electrolytes which may not comprise any non-ionic solvents.Most preferred non-ionic solvents are propylene carbonate, ethylenecarbonate, dimethyl carbonate, ethylmethyl carbonate, dipropylcarbonate, diethoxy ethane, sulfolane, methyl sulfolane,cyanoethylsucrose, 3-hydroxypropionitrile, 3-3′-oxydipropionitrile,2-methylglutaronitrile, acetylbutyrolactone, and gamma-butyro lactone.Flourinated carbonates may also be used, some examples are methyl2,2,2-trifluoroethyl carbonate (MTFEC), ethyl 2,2,2-trifluoroethylcarbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl2,2,2,2

,2

,2

-hexafluoro-isopropyl carbonate (MHFPC), ethyl2,2,2,2′,2′,2′-hexafluoro-isopropyl carbonate (EHFPC), anddi-2,2,2-trifluoroethyl carbonate (DTFEC). Many other solvents which canbe used as co-solvents are listed in U.S. Pat. No. 6,245,262 asplasticers. In addition, the ionic liquid component may itself compriseof more than one ionic liquid and may have same or different anions.

Anodic and cathodic compounds for EC devices of type shown in FIGS. 1, 2and 3 can be chosen from various candidate materials. Some examples ofanodic dyes are compounds that comprise pyrazoline, metallocene,phenylenediamine, benzidine, phenoxadine, phenothiazine, tetrafulvaleneand phenazine; and cathodic compounds that comprise viologen andanthraquinone. More details on these with specific examples andderivatives may be found in Shelepin-1 (Shelepin, I. V., et al,Elektrokhimiya, vol 13, no 3, (1977) p-404), Shelepin-2 (Shelepin, I.V., et al, Elektrokhimiya, vol 19, p-1665, (1983)), U.S. Pat. Nos.6,392,783; 6,445,486; 6,496,294, European patent application 0055012, WO01/63350, U.S. Pat. No. 4,902,108 and U.S. Pat. No. 5,140,455. One hasto ensure that these dye materials solubilize in the electrolyticmedium, and it is preferred if the dyes are ionic (i.e. have an anionand a cation), such as viologen salt, the anion of the dye be the sameas the anion of one of the ionic liquid(s) in the electrolyte. If morethan one viologen salt is used it is preferred that at least one ofthese has the same anion as that of the ionic liquid in the electrolyteor one of the ionic liquids in the electrolyte. As disclosed inapplication Ser. No. 10/600,807 and provisional application (ApplicationNo. 60/502,133), the preference is to use at least one bridged dye. Abridged dye has more than one functionality in a single molecule whichmay be anodic and cathodic functionalities, or where thesefunctionalities may be combined with UV stabilizing moeties. Preferredclasses of bridged dyes with anodic and cathodic moieties are those,which comprise of ferrocene (anodic) and viologen (cathodic) moiety(abbreviated as Fc-Vio). Examples of these (Fc-Vio) are in the abovepatent applications and in U.S. Pat. No. 6,519,072 and in Meyerhans etal. (Meyerhans, A., et al., Helvetica Chimica Acta, Vol 65 (1982),p-2603). For use in EC devices with BMP as ionic liquid in theelectrolyte, a preferred anion is imide. Another preferred combinationof anodic and cathodic moiety is those having dihydrophenazine (anodic)combined with viologen (cathodic) (abbreviated as Ddp-Vio). Examples ofthese are given in U.S. Pat. No. 6,241,916 and in Michaelis, A., et al.,Advanced Materials, Vol 13 (2001) p-1825. The bridged dyes may have anyanions which are listed above for the ionic liquids, however, the mostpreferred ones are imide, beti and methide. As an example, a bridged dyeFc-Vio with imide anions will be abbreviated as Fc-Vio imide. Otherpreferred dyes are charge transfer compounds including those withtitanium (III), vanadium (III), vanadium (IV), iron (II), cobalt (II),copper (I), silver (I), indium (I), tin (II), antimony (III), bismuth(III), cerium (III), samarium (II), dysprosium (II), ytterbium (II), oreuropium (II) as described in patent application Ser. No. 10/600,807 andprovisional application (Application No. 60/502,133). In all cases it isalso preferred that when electrolytes comprise ionic liquids, the anionof these should be similar to the anions of the dye. Preferred anionsare triflate (CF₃SO₃ ⁻), imide (N(CF₃SO₂)₂ ⁻), beti ((C₂F₅SO₂)₂N⁻),methide (CF₃SO₂)₃C⁻), tetraflouroborate (BF₄ ⁻), hexaflourophosphate(PF₆ ⁻), hexafluoroantimonate (SbF₆ ⁻), C₂H₅SO₄ ⁻ and hexafluoroarsenate(AsF₆ ⁻) of which imide, methide and beti are most preferred and thesealso result in high hydrophobicity making electrolytes less susceptibleto moisture ingress. Specific examples of dyes in all these classes aregiven in the above-identified patent applications.

It is well known in the art to use complimentary coloring materials tocontrol color. In those devices where only EC layers are used for redoxreactions (see FIG. 4), complimentary coloring materials are often used.One may use a layer with tungsten oxide with a counterelectrodecomprising nickel oxide, vanadium oxide, etc. As an example, tungstenoxide colors blue in the reduced state and nickel oxide colors brownwhile vanadium oxide colors to a yellow tint when oxidized. Thus, atungsten oxide and nickel oxide based device colors to a more neutralcolor, whereas a tungsten oxide device with vanadium pentaoxide colorsto a green color. Further, these layers may be doped for color control(as an example tungsten oxide doped with zirconium oxide, molybdenumoxide or vanadium oxide colors to a more neutral color) and whentungsten oxide is doped with small amounts of chromium oxide, copperoxide and cobalt oxide there is a shift in the UV spectrum, which doesnot cause a visible color change, but improves the UV stability (e.g.see U.S. Pat. No. 6,266,177). In those devices where dyes are used inthe electrolyte (with or without redox layers), several dye combinationsmay be used to get the desired color. These electrolytes may comprisemore than one cathodic dye and/or more than one anodic dye to achievethis purpose. Such devices for conventional solvent electrolytes aredescribed in European patent application 00758929/EP B1, U.S. Pat. No.6,288,825 and Shelepin-2. U.S. Pat. No. 6,288,825 and Shelepin-2particularly discuss those systems where a third dye (anodic orcathodic) is used in addition to at least one anodic and one cathodicdye. In European patent application 00758929/EP B1 a tungsten oxidebased mirror is described with two anodic dyes in the electrolyte togive the device a more neutral-color appearance using a ferrocene incombination with phenothiazine in a molar ratio of about 1:1 to about1:10. There is no restriction on using the same principles in deviceswith ionic liquids as long as the components are compatible. In oneaspect the range of dyes can be expanded by using those dyes thatrequire higher redox potentials and may have led to irreversibleelectrochemical reactions in conventional electrolytic fluids. It ispreferred that the dyes for color control of this invention use at leastone bridged dye in the electrolytes for EC devices of the type shown inFIG. 1. The preferred classes of bridged dyes were described above. Onemay add more than one bridged dye, such as Fc-Vio and Ddp-Vio. Forexample, either one of the two bridged dye classes named above may beadded along with non-bridged dyes in the electrolyte, where thenon-bridged dyes preferably belong to one of the class selected fromphenazine, ferrocene, phenothiazine and hydrazone for anodic dyes; andviologen, and anthraquinone based dyes for cathodic ones.

As for conventional solvent-based devices, anodic and cathodic dyes mayalso be modified in a way so that UV energy receptors (typically knownUV stabilizer moieties such as benzophenones, benzo-triazoles, etc.) canbe covalently attached to them. This is another class of bridged dyes.These receptors absorb the UV radiation before they damage the redox orthe coloring moiety. Such dyes are called bridged dyes as they combinemore than one function in the same molecule. Such modified dyes can beused in electrolytes comprising ionic liquids as well. Their use innon-ionic solvents is described in U.S. Pat. No. 6,362,914. For example,this patent describes a cathodic compound where a viologen is modifiedby attaching an energy receptor. This material is1-methyl-1[1-benzotriazole-2-hydroxy-3-t-butyl-5propyl(propionate)-[benzene]]-4,4-bipyridinium bis tetrafluoroborate.For use in ionic liquid where the anion is imide, it is preferred thatthis material be ion exchanged so that the tetrafluoroborate ion isexchanged for imide ion. The advantage of doing this is to increase theUV stability of the device, and impart even better UV stability to thedye containing devices when colored in presence of solar radiation. Inaddition, there is a possibility that such devices comprising ionicliquids with low absorbance in the UV may not require additional UVstabilizers. Bridged dyes may have both anodic and cathodic moieties inthe same molecule in addition to the covalently attached UV energyreceptors.

A bridged molecule can be so tailored (donor/acceptor duo) so thatinherently it has good UV stability (Fifth International meeting onElectrochromism (IME5), Denver, 2002, and also published, see Akita, S.et. al., (Akita, S. et. al., Solid State Ionics, Vol 165 (2003) p-209).When such dyes are used in EC devices for mirrors additional UVstabilizers may not be required. For example a UV stable dye is producedwhen a ferrocene moiety is coupled with a viologen moiety using anappropriate linker or bridge. We have also discovered that the UVstability is also controlled by the selection of the anion of the dye,and the preferred anions are imide, beti and methide. These moleculescan also be used in the ionic liquids and it is preferred that the anionassociated with this molecule (or with the viologen moiety) is similarto the anion of the ionic liquid. As an example a preferred anion isimide when used with ionic liquid comprising of imide ions. Further,these molecules i.e., where the anodic and the cathodic entities are ina single molecule may also be bridged with energy receptors to increasetheir UV stability even more. It is preferred that the UV stabilizermoiety be linked to the same bridge which joins the two redox moeties.

Typically the molar concentrations of the anodic and the cathodiccompounds in the electrolyte are largely equivalent. This condition isautomatically fulfilled when a balanced bridged dye compound is used,i.e., a dye which has one anodic and one cathodic moiety. The imbalancein the concentration of the anodic and the cathodic moieties in bridgeddye comprising electrolytes may be caused by use of imbalanced-bridgedcompounds (i.e. single molecules with more of one type of moiety) or byfurther adding dyes with only anodic or cathodic nature. A preferredimbalance of anodic to cathodic moieties is in a range of about 1:2 to2:1. This selection may be largely based on empirical results fromcycling, durability and optical tests. For conventional electrolyticsolvents, U.S. Pat. No. 6,353,493 and Ushakov, et. al. (Ushakov, et.al., Elektrochimiya, vol 21, p-918, 1985) describe that theconcentration balance of electroactive compounds is better determined byestablishing their current limiting concentrations based on theirmobility. Since, the mobility of the dyes may change in ionic solventcomprising electrolytes, similar principles can also be used toestablish their concentrations if desired.

Additional components may be added to the electrolytes which couldenhance kinetics. These materials help in oxidizing the reducedelectrochromic species in the cell or help reduce the oxidizedelectrochromic species in the cell. These additives are described inU.S. Pat. No. 6,266,177. The preferred additives in this application aremetallocenium salts such as ferrocenium salts and salts of ferroceniumderivatives. These additives and their concentrations are chosen so thatthey do not impart too much color to the cell in the bleached state.Such additives have also found use in keeping the bleach transmissionhigh in oxygen atmosphere under high pressure testing, e.g., U.S. Pat.No. 6,486,998. In both of the foregoing patents several materials aredescribed which facilitate reversing of the colored electrochromicspecies. One or more such additives can also be used in the devices ofthis invention. These additives can be used in the present invention aslong as they are soluble. One may also use salts of bridged dyes, e.g.,Fc⁺-Vio. For example if metallocenium salts are used, it is preferredthat their anion is the same as that of one the ionic liquids comprisingthe electrolyte. Typically, the desired concentration of such anadditive is preferably lower than 5 times the concentration of the dyes,and more preferably less than 10 times the concentration of the totalamount of anodic or cathodic dye. These additives are preferablyreversible reducing or oxidizing agents. In addition one has to becareful in the choice of these additives that they are stable to UVlight when used for outdoor applications or where the devices aresubjected to UV.

In most EC devices where the EC activities are associated with dyes inthe electrolyte, the attenuation of the solar radiation is in thevisible range only. However, for energy efficient windows it isimportant to be able to also reduce the transmission in the NearInfrared (NIR) region as almost half of the solar energy is comprised ofthis radiation. This could be done by incorporating electrochromiclayers into the device (as shown in FIGS. 2-4) which attenuate in theNIR region such as those comprising of tungsten oxide, conductivepolymers (e.g., polyaniline and its derivatives); by depositing metalsat the electrodes which block in a wide wavelength range; or by usingdyes which absorb in the NIR radiation. More on IR blocking materialsfor example are respectively given in U.S. Pat. No. 5,729,379 (for metaloxide based layers), U.S. Pat. No. 6,256,135 (for conductive polymerbased layers) and U.S. Pat. No. 6,256,135 (for metal depositing device).WO 99/45081 describes dyes which may be added to the electrolytes toabsorb in the NIR. The electrochromic layers do not requiremodifications to be used with ionic liquids comprising electrolytes aslong as there is good adhesion to the electrolyte layer if this layer issolid. The NIR absorbing dyes should be soluble in the electrolyte.

Use of Solid Electrolytes in Mirrors

Solid electrolytes promote safety in mirrors by containing both theelectrolyte and broken shards of substrate in case these break onimpact. When the front glass substrate is lower than one mm inthickness, then the electrolyte should preferably be a solid to providesuperior mechanical integrity. Solidification of the electrolyte can bedone in many ways including polymerizing a monomer which is dispersed inthe electrolytic medium and it is polymerized after filling the cavity,for example see U.S. Pat. No. 6,420,036. Although several ways aredescribed in this patent, a preferred way to transform theelectrochromic polymeric solid films is by in-situ polymerization. A lowviscosity electrochromic monomer composition is filled in apre-fabricated cell cavity which is then exposed to electromagneticradiation and/or by heat for in-situ polymerization. Alternatively,preformed solid films of polymers plasticized with electrolyticcomponents may also be laminated between the substrates carrying the twoelectrodes, e.g., see U.S. Pat. No. 6,639,708 and WO 03/003110.

Thus the monomer compositions for filling cavities in the inventiondisclosed here will typically comprise of ionic liquid, redox dye(s),and polymerizable monomers. Optionally, UV stabilizer(s), catalysts,initiators, non-ionic cosolvents and other salts may also be included.Some of the dyes may also be polymerized into the polymer network. Tokeep the polymerization caused shrinkage low, it is preferred that themonomer composition should have molecules which participate in thepolymerization reaction less than 25% by weight of the total compositionand more preferably less than 10% by weight. An example may be use of2-hydroxy ethyl methacrylate (polyHEMA) with ethylene glycolmethacrylate as the crosslinker and an appropriate catalyst such asbenzoyl peroxide which are all dissolved in the electrolyte. When thisliquid composition is placed in the EC cavity then the polymerization isconducted in-situ, e.g., by heating. Polymers for the preferred ionicliquids of choice are generally fluorinated, this is in part to havegood solubility and UV stability. Polymers and copolymers could beformed by in-situ polymerizing tetrafluoromethylacrylate; 1H, 1H, 7H,Dodecafluroheptyl methacrylate; and a variety of fluorinated polyethers.Functionalized fluoroethers are available from Solvay Solexis(Thorofare, N.J.) under the tradename of Fluorolink. Functionalizedfluoropolyethers may be crosslinked using various chemistries such byusing comonomers so that reactions with epoxy and isocyanats groupsresult in polymer formation. The comonomers may be non-fluorinated.Generally, the cross-linker concentration is less than 5 mole percent(preferably less than 2 mole %) based on all monomers. The monomers forpolymerization may polymerize by addition or condensationpolymerization. Those condensation polymerizations are preferred whichdo not release any new small molecules such as water and gases. Some ofthe preferred mechanisms are reactions between amines and epoxies,amines and isocyanates, isocyanates and hydroxyl groups. Additionreactions may be ring opening polymerizations or through the opening ofunsaturated bonds and rings. To form a polymer which will solidify atlow concentrations, those systems are preferred which form a threedimensional network. This means that for condensation systems thereshould at least be one monomer which is trifunctional or of higherfunctionality. For polymers forming networks by addition polymerization,use of polyfunctional monomers (those monomers which have at least twopolymerizable unsaturations) is required. A number of chemistries whichmay be employed here are listed in U.S. Pat. No. 6,245,262. Other thanthe monomers, appropriate catalyst may also be required. The details ofmaterials, chemistry and reactions are well known and may be found in astandard polymer chemistry book (e.g., see Polymer Chemistry: AnIntroduction, by M. P. Stevens, Oxford University Press (1998). For lowshrinkage it is preferred that those monomers be used which have highmolecular weight (e.g., functionalized pre-polymers and oligomers),typically greater than 2,500, and preferably greater than 5,000. Suchmonomers may raise the viscosity which may be overcome in thebackfilling process of the cavities by increasing the temperature (seeUS patent application 2004/0021928).

Formation of Solid Electrolytes by Multiphase Systems

A novel way of forming clear solid electrolytes is by the use of thosepolymers (including copolymers) which result in multi-phase structure,meaning two or more phases. One phase is readily soluble in theelectrolyte at all temperatures in which the device needs to function,and at least one phase is insoluble or has low solubility in thistemperature range. The fall out of the second phase from the solutionmay result in crystallization of this phase or even a physical orchemical bonding which may require elevated temperature to disperse.Thus, the second phase has a distinct glass transition temperature (Tg)or melting point. Addition of polymers which form single phase tothicken electrolytes is not new, e.g. see Shelepin-3 (Shelepin, I. V.,et. al., Elektrokhimiya, Vol 13, (1977), p-404), U.S. Pat. Nos.5,142,407; 5,145,609 (e.g., see Table 1 in both of these publications)and U.S. Pat. No. 5,801,873. Viscosity modification by adding polymersthat form single phase results in a continuous increase in viscositywith the amount of additive. Further, this viscosity is sensitive totemperature. A highly viscous material at room temperature may flowfreely at 50° C. Further if large amounts (typically greater than 30%)of solid polymer is added for thickening, then filling such fluids incavities is difficult and also leads to considerable slow down in devicekinetics. However, the change in viscosity with addition of polymericmaterial is very different for a system forming the two phases whenobserved below the Tg or melting point of the second phase. With smallamount of polymeric addition a viscosity rise is seen, however as theadditions continue, suddenly at a particular concentration viscosityrises rapidly and is not measurable. This happens when there issufficient amount of polymer which is able to form a continuous networkof the 2 phase structure, and the domains of the 2^(nd) phase areinterconnected by polymer chains compatible with the electrolytic phasethroughout the bulk of the electrolyte body. This is similar to theon-set of gel-point in the formation of crosslinked systems, defined asthe first instance when an infinite molecular weight body is firstformed (e.g., see P. J. Flory, Chapter 9, Principles of PolymerChemistry, Cornell Univ. Press (Ithaca, N.Y.), 1953). One may useviscosity modifiers in addition to materials that result in formation ofa second phase. For 2 phase systems, the present invention contemplatesa first phase as the one which is more compatible or well dispersed inthe electrolyte, and the subsequent phases, such as second phase beingless soluble in the electrolyte. At least one of the subsequent phaseskeeps parts of the polymeric chains physically locked which results inan overall solidification of the electrolyte.

There are several examples of polymers forming multi-phase systems.Thermoplastic elastomers formed from styrene/butadiene/styrene blockcopolymers where butadiene forms the continuous flexible phase andstyrene blocks preferably agglomerate in embedded domains which are hardand only become soft above the Tg (glass transition temperature) of thepolystyrene which is around 100° C. To dissolve these polymers in liquidelectrolytes one may have to use elevated temperature and/or severeagitation, such as by using ultrasonic mixers. Once these are put incavities, the second phase forms by one or more of cooling or absence ofmotion or shear. In the example above, when the polymer is introduced inthe electrolytic environment, the properties of the second phase may bedifferent as compared to in the bulk phase. For example, the secondphase may incorporate one of the components of the electrolyte, or thisphase may take up solvent in a different proportion as compared to theamorphous phase, or there may be stresses due to the forces exerted bythe amorphous phase swelling, etc.

For electrochromic devices the cavities are typically formed by twoconductors as shown in FIGS. 1 through 4. Generally, these substratesare parallel to one another. The distance between them is controlled byperimeter sealant or by putting some spacers between the two plateswithin the active area of the device. These spacers may be made out of amaterial, e.g. a polymer, which may later dissolve in the electrolyte.As discussed above and in all automotive EC mirrors produced today, theliquid electrolyte may be introduced by back filling through a hole leftin the perimeter seal, which is plugged after sealing. When polymerscapable of forming two or more phases are added to the electrolytes, thecavities are preferably backfilled at temperatures higher than themelting point or the Tg of the second phase. If even at elevatedtemperatures the viscosity is too high for backfilling, one may injectthe electrolyte under pressure into the cavity. Thus, for making ECdevices including automotive mirrors by injection process, it ispreferred that the perimeter sealant has at least two openings, whichare preferably located at the two diagonal or long ends of the device.One of these is for filling by injection and the other is for venting.One may optionally flush the cavity before filling with an inert gassuch as nitrogen or argon and then fill the cavity. During filling onemay apply vacuum on the vent port to aid filling. After filling both theopenings are plugged. There may be more than two openings depending onthe shape and size of the cavity so that multiple injection and/or ventports may be required for uniform filling. When filling with fluids atelevated temperatures the cavities may be pre-heated. The plug holes maybe in the substrates or in the main seal. After filling the cavities,they may be heated above the melting point or Tg of the second phase andthen cooled to reform the second phase. This may be beneficial to removeany irregularities and stresses caused by the filling process. Thus thepreferred process is to introduce the electrolyte in a liquid form intothe cavity which comprises of perimeter sealed two substrates which arespaced apart. The liquid is converted to a solid after it is introducedinto the cavity as it forms a multi-phase system.

For those devices which require good optical properties, the electrolyteshould be clear and free of visible haze. Haze is particularly morevisible in mirrors than in windows and more so from glare sources suchas lights from road traffic. It is preferred that haze in these mirrorsbe lower than 1%. Typically this is achieved by having the second phaseto be smaller in size than the wavelength of the visible light, i.e.,smaller than 400 nm or preferably below 100 nm so that the light is notscattered and clarity is maintained. Crystallizable copolymers ofvinylidenefluoride (VF) and hexafluoropropylene (HFP) can result in twophase systems. Alternatively, if the size of the second phase is largerthan 400 nm, the refractive index of the second phase should match thatof the electrolyte (typically within 0.05 or more preferably within0.01). In this case blocks of PolyVF crystallize while blocks ofattactic polyHFP and random copolymer sequences of VF and HFP remainamorphous and more accessible to the liquid electrolyte. These blockcopolymers may be linear or branched. The blocks which crystallize maybe distributed along the main chain of the polymer or they may only belocated in the side chains (branches or grafts). Block copolymers may bealso formed of polymethylmethacrylate and PolyHEMA, where the formerpolymer may form the second phase and the latter may be soluble in theelectrolyte. If the electrolyte composition is such that it solubilizespolymethylmethacrylate, then it may be substituted with another polymer,e.g., polystyrene and polyacrylonitrile. When linear polymers are usedthen multiblock or triblock colpolymers are preferred. A particularlypreferred arrangement is a triblock polymer where the two ends of thechain have those blocks which form the second phase which is not solublein the electrolyte and the block in the middle is soluble in theelectrolyte. The length of the end blocks may be 10 to 1000 of unitslong (monomer repeat units), and preferably less than 100 units. Theones in the center may be 100 to 10,000 units long. When graftcopolymers are used then the blocks forming the hard domains (secondphase) may reside at the end of backbone polymer chain or in the graftedbranches. In addition, random copolymers which do not form a secondphase may also be optionally added to change properties and size of thesecond phase. Polymer content in the electrolyte is generally in therange of 2 to 30% by weight of the electrolyte. A more preferred rangeis between 5 and 25%. More than one polymer forming a second phase maybe added to solidify the electrolyte. One or more of these may form thesecond phase. There may also be additives so that when the second phaseis formed, the chains in this phase are optionally crosslinked. Thereare several grades of commercial polymers comprising at least one of VFand HFP that are available for solidification. Depending on thetemperature range of device operation and its interaction with the otherelectrolytic components, one or more of these may be selected. Atofina(Philadelphia, Pa.) sells these under the tradename of Kynar™ and someof the grades are 301F, 741 LBG and Kynar Flex 2801 and these may alsobe obtained from Solvay (Thorofare, N.J.) under the trade name of SOLEF™and some of the grades being 1015, 6020, 21216, 20816, 20615 and 11008.Two phase systems may also be formed using homopolymers where the secondphase forming domains are isotactic or syndiotactic, and the onesforming the more soluble phase with the electrolyte are atactic. When amultiphase system is used to solidify the electrolyte, then it ispreferred that the Tg or the melting point of one of the phase in theelectrolyte is greater than 50° C. and for some applications such asautomotive glazing it may be above 85° C. A preferred EC mirror systemcomprises a single compartment, self erasing device (FIG. 1) or acompartment comprising one electrochromic coating (FIG. 2) which isfilled with a clear solid formed by a multiphase polymer as describedabove. The electrolyte in the compartment may comprise anodic andcathodic dyes in addition to UV stabilizers. These dyes may also bebridged.

Alternative Methods to Immobilize Liquid Electrolyte

Yet another method to immobilize the electrolyte in the cavity is byusing a sheet of polymeric open cell foam or an aerogel sheet or a sheetwhich may be able to soak liquid electrolytes. This sheet is cut in theshape of the cavity and then assembled inside of the cavity. Optionally,this sheet may also act as a spacer between the two plates. It ispreferred that the electrolyte have a refractive index within 0.05,preferably within 0.01 and most preferably within 0.005 of the materialof which the foam is made out of to reduce the scattering of light. Theelectrolyte is filled in a cavity comprising this foam (e.g. bybackfilling through a hole left in the perimeter seal) and the liquidpermeates through the pores. After filling the fill hole is plugged.Since the refractive index between the liquid electrolyte and the foammaterial is matched, one does not notice the presence of foam. In caseof device breakage, the electrolyte may be held within the foam and notdrip.

Yet another method to immobilize the electrolyte is by depositing acoating on one of the conductive substrates. This coating is removedfrom the perimeter where the adhesive would be dispensed to form thecavity. This coating is preferably crosslinked or is of a polymercapable of forming multiple phases (as described above). Thecross-linked polymer swells and fills the cavity as it absorbs theelectrolyte during the filling process or subsequent to filling aided bytemperature and/or time. The two phase polymer gets dispersed in theelectrolyte and solidifies the entire electrolytic mass.

All of these novel ways of solidification are applicable to alldifferent types of EC devices including the single compartment device oftype shown in FIG. 1. EC devices where a material is deposited on one ofthe electrodes (e.g. see U.S. Pat. No. 5,923,456) are also included.Active optical devices such as electroluminscent, photoelectrochromicand photochromic devices employing electrolytes or liquid mediums asgiven in U.S. patent application Ser. No. 10/741,903 may also besolidified using the present disclosure. In general, optical filters orglass laminates where solid interlayers are preferred between twosubstrates can also be made using these principles.

EC Mirror Electrodes and Busbars

EC Mirror Electrodes and Methods to Deposit them

Typically electrochromic mirrors, for automotive and othertransportation use are made using a cell with two transparent conductorsfacing inwards and in contact with electrolyte and/or redox layers,e.g., as described earlier in FIGS. 1 and 2. Generally, the reflectivemetal layer is outside the active electrochromic cell as shown in FIG.5a . This figure shows an EC mirror device based on the principles ofFIG. 1. The mirror is constructed of two substrates shown by 50 a. Theinward facing surfaces of these are coated with transparent conductivecoating 51 a. The two substrates are joined by an electrolyte 52 a.Layer 53 a is reflective. In addition, the four surfaces of the twosubstrates are marked 1, 2, 3 and 4 numbering these surfaces. Thereflector 53 a is located on the fourth surface and the device is viewedfrom the side of the surface 1. This is called a fourth surface mirror.This figure also shows the connectors 54 a and 55 a along with a powersupply 56 a. The connectors 54 a and 55 a make contact with the twoconductive electrodes 51 a.

Increasingly, the reflective layer is substituted for the interiortransparent layer located on surface 3 to work both as a reflector and aconductor as described in WO 00/23826 and in U.S. Pat. Nos. 6,245,262;5,668,603 and 3,280,701. This means that a conductive reflector willreplace the transparent conductor on surface 3, and are called thirdsurface mirrors. Generally the preferred metallic layers should be suchthat they do not react electrochemically during the oxidation andreduction of the electrochromic or other electrochemically activematerials and do not corrode at the perimeter (outside of the cell)where they are attached electrically. Generally the preferred materialsin commercial devices are rhodium, silver, silver alloys, aluminum,aluminum alloys and chromium. To prevent corrosion (either inside oroutside the cell), multiple stacks are used where some of the metals,particularly silver and aluminum are overcoated with a layer of atransparent conducting metal oxide (e.g. ITO, antimony doped tin oxide).The transparent layer prevents the electrolyte in contacting the metallayer and hence prevents corrosion. In the above reflective metalchoices chromium and rhodium are generally used for outside automotivemirrors due to their lower reflectivity. In all of these patents andapplications, generally two or more metal layers are used forreflection. This is perhaps, as pointed out in U.S. Pat. No. 5,668,663,because there is a need for using a tie layer to increase adhesion ofmore reflective materials such as silver and aluminum. The idea of usinga tie layer is not novel for these metals deposited on glass by physicalvapor deposition (e.g., evaporation and sputtering), where a morereactive metal such as chromium or titanium is first deposited to reactwith the surface active groups on glass such as bound water and —OHgroups. A third surface single compartment device is shown in FIG. 5b .The two substrates are shown by 50 b, electrolyte by 52 b, the twopowering leads by 54 b and 55 b and the power supply by 56 b. Thetransparent conductive coatings are shown as 51 b. One of these isdeposited on a reflective layer 53 b. The reflective layer waspre-deposited on the substrate after depositing a tie layer 57 b. Thetransparent conductive coating which is deposited on the reflectivelayer is only for electrochemical protection, thus its conductivity maybe lower, or composition be different or microstructure be different, orthickness be different as compared to the transparent conductor on theother substrate.

However, according to the present invention, one can avoid thedeposition of tie layers by removing these reactive groups and/orsurface modification. One way to remove reactive groups is to treat thesubstrate before metal deposition by high energy processes such as byion treatment (e.g. oxygen, xenon, nitrogen and argon ions) and plasmatreatment (e.g., argon, xenon, ammonia and oxygen plasma). Thistreatment is preferably done in the same chamber where the metal isdeposited, and the metal deposition begins after the treatment processwithout exposing the activated surface to ambient atmosphere, e.g., bynot breaking the vacuum around the substrate between the activation anddeposition process. The ion and plasma treatment may even continueduring the deposition of the metal to ensure uniform nucleation, highdensity and low stresses. During these treatments and depositionprocesses the substrates may also be optionally heated (e.g., from 50 to400° C.). Typical metal thicknesses are in the range of 50 to 500 nm.Stelmack, et. al. describe ion assisted process and the equipment usedin more detail (Stelmack, L. A., Nuclear Instruments and Methods inPhysics Research B37/38 (1989), p-787). A third surface singlecompartment device is shown in FIG. 5c without using a tie layer. Thetwo substrates are shown by 50 c, electrolyte by 52 c, the two poweringleads by 54 c and 55 c and the power supply by 56 c. The transparentconductive coatings are shown as 51 c. One of these is deposited on areflective layer 53 c. The transparent conductive coating which isdeposited on the reflective layer is only for electrochemicalprotection, thus its conductivity may be lower, or composition bedifferent or microstructure be different, or thickness be different ascompared to the transparent conductor on the other substrate.

One type of ion-source that may be used for this purpose is calledEnd-Hall ion source. End-Hall ion sources are made by several companiesand may be installed in the metal deposition chambers. Some of these areKaufman & Robinson (Fort Collins, Colo.), Advanced Energy Systems Inc(Medford, N.Y.) and VEECO (Woodbury, N.Y.). A more preferred type ofEnd-Hall source are gridless type. These sources are low acceleratingvoltage (usually lower than 500 eV and preferably lower than 300 eV, andmost preferably lower than 100 eV) and high current (usually greaterthan 1 A), resulting in surface ion flux of about 1-5 mA/cm². The ionenergy in eV for an accelerating voltage of 500V is equivalent to 500eV. These sources are compatible with a variety of physical vapordeposition (PVD) methods such as thermal evaporation, e-beamevaporation, sputtering, magnetron sputtering, etc. End-Hall ion sourcesare described in Kaufmann, et. al (Kaufmann, H. R., Journal of VacuumScience and Technology A, vol 5 (1987) p-2081), U.S. Pat. Nos. 6,608,431and 4,862,032.

Once the metals are deposited, an optional coating of a transparentconducting oxide may be deposited. This is done, because several of themetals may react with the electrolyte when the devices are powered, andthe oxide conductors are more inert. The use of End-Hall source duringthe deposition of these oxide conductors results in high conductivityand density without the use of high temperatures (i.e. excess of 250°C.) or use of reactive gases (such as oxygen) or post treatment at thesetemperatures in reducing and/or oxidizing atmosphere. An example ofpreferred transparent conductive oxide with high electrochemicalstability is an alloy of zinc oxide and aluminum oxide (e.g., AZOY™ fromGFE Metalle and Materialien (Germany)). Indium-tin oxide (ITO), tinoxide doped with antimony or fluorine may also be used. Typicalthickness of oxide conductors is from 30 to 300 nm.

Although plastics or glass may be used for the substrates due to theirlightweight, for automotive EC mirrors, preferred substrates are glassdue to their scratch resistance, inertness, rigidity, thermal stabilityand low permeability to gases and water. In this application “glass” forsubstrates refers to inorganic glasses, such as soda-lime glass,borosilicate glass, etc. Alternatively one may also use a reflective andconductive foil laminated to another substrate, which may be made of aplastic, glass, ceramic or any other material. Alternatively a machinedmetal plate which has high reflectivity on one side (e.g. polished) mayalso be used. The metal foil or laminate may have a conductive oxidecoating to impart inertness. The use of laminated or metal plates alsoincreases the scatter-resistance of the mirror devices.

The present invention allows one to use many different metals withouttarnishing including silver and silver alloys, aluminum and aluminumalloys, rhodium, chrome, tantalum, nickel and its alloys, stainlesssteel, etc., which are in contact with electrolyte. The devices of priorinvention typically use at least one salt or a dye salt with an anionPF₆ ⁻, CF₃SO₃ ⁻, BF₄ ⁻, and ClO₄ ⁻. These anions are corrosive toseveral metals, thus special alloys and overcoats are required.According to the present invention, the use of “imide” orbis(trifluoromethylsulfonyl)imide (N(CF₃SO₂)₂ ⁻); “beti” orbis(perfluoroethyl sulfonyl)imide ((C₂F₅SO₂)₂N⁻); “methide” ortris(trifluoromethylsulfonyl)methide (CF₃SO₂)₃C⁻) as anions in theelectrolytes is preferred. Preferred ionic liquids based on such anionsand saturated quarternary ammonium cations do not corrode the metalsdescribed above upon contact. Many of these are hydrophobic, thuscorrosion due to moisture ingress in the primary seal is also reduced.

Corrosion resistant alloys of silver for use in automotive mirrors aredescribed in U.S. Pat. No. 5,818,625 and in US patent applications20030227250 and 20040005432 where silver is alloyed with gold,palladium, rhodium, platinum copper, silicon, copper+zinc and copper+tinand several other materials. These alloys may be used with thisinvention but a more preferred alloy for electrochromic mirrors is ofsilver with at least one lanthanide element. Lanthanides have atomicnumbers from 57 to 71 in the periodic table, and a particularlypreferred lanthanide is neodymium. The preferred doping percentage oflanthanide is less than 15%. Corrosion resistant aluminum alloys mayalso be used for mirror electrodes. An advantage of aluminum is lowercost as compared to silver. Although “aluminum alloys” is listed as acategory in U.S. Pat. No. 5,910,854, specific elements to which aluminummay be alloyed for EC mirror application is not given, which need tohave superior corrosion resistance, particularly that resistnon-reversible electrochemical activity. Preferred alloying elements forthis application are manganese, iron, silicon, magnesium, zinc andchromium. Of these particularly preferred are manganese, magnesium,silicon, chromium and zinc. These alloys may also have copper, butaluminum alloyed only with copper are not too durable to corrosion.There may be more than one alloying elements, and some preferredcombinations are additions of magnesium+manganese, magnesium+silicon ormagnesium+zinc. Preferred combinations also include further addition ofchromium, to magnesium+silicon and magnesium+zinc. Some of the preferredalloys of aluminum are 3xxx, 5xxx and 6xxx series. Some of the preferredgrades in these classes are 3003, 3004, 5005, 5050, 5052, 5083, 5086,5454, 5456, 6005, 6061, 6063 and 6101. The alloys may be coated bysputtering or evaporation on to the substrates, and may use the ionassistance before or during the coatings deposition as discussedearlier. Generally, the concentration of alloying materials in aluminumis less than 15% and more preferably less than 4%. In silver theconcentration of the alloying elements is generally also less than 15%.All percentages for alloys in this disclosure are molar (or atomic).

Busbars and Methods to Form them

Metal layers may also be used as busbars on the perimeter of the clearsubstrate. In a preferred process the third surface reflector and theperimeter busbar for the front substrate may be formed in a singleoperation, as described in U.S. Pat. No. 5,724,187. As shown in FIG. 6a, the front substrate 60 is pre-coated with transparent conductor 61 andthe rear substrate 65 for the rear reflector/conductor is placed in astacked relationship, while exposing most of the perimeter of theconductive coating. This stack is coated with a metal as shown in FIG.6b . The metal is coated from one side so that it coats the surface of65 as shown by 66 and also the exposed edges of the front substrate asshown by 62. The back and the front substrates are separated and therear substrate is flipped so that 66 faces 61 as shown in FIG. 6c . FIG.6c shows the device which is made using the principles of FIG. 1.Substrate 65 is slightly translated so that after these are bonded usinga perimeter adhesive 69, electric connecting wires may be attached tothe conductive edges of the two substrates shown by 63 and 67.Electrolyte in the assembled device is shown as 64 which is introducedby backfilling or lamination as discussed earlier. Alternatively theremay be notches or corners in substrates so that translation or rotationmay expose areas for connection to electrical wires. This methodtypically yields a good reflector and a conductor, but for most casesthis may not be adequate for an all around busbar for the transparentsubstrate, as it is too resistive due to the thickness limitations ofthe metal which is deposited. Using PVD, typical metal thicknesseconomically achievable are generally less than 500 nm and usuallyaround 100 nm.

Consider an EC device with a perimeter of 60 cms. A chrome busbardeposited all around the perimeter of thickness of 100 nm will yield aconductor with surface resistance of about 1.3 ohms/square and theresistance of a busbar strip 30 cm long and 2 mm wide will result in aresistance of 25 ohms. The busbar in this geometry and composition willnot be too effective when used on a substrate with similar resistivitytransparent conductor (transparent conductor measured in ohms/square).This is because when this busbar is connected with a powering cable on asmall area (less than 1 cm of busbar width) the potential drop along thebusbar will be large. Effectiveness means that it will not be able topromote a uniform coloration and bleach, where the coloration in thevicinity of the connection will be faster and deeper. It is preferredthat the resistivity of the busbar for a length equivalent to half thedevice perimeter and in appropriate width (generally less than 5 mm)should preferably be less than a factor of 2 as compared to the surfaceresistivity of the transparent conductor. A more preferred factor is 10,and a most preferred factor is 25. The resistivity of the busbar may bechanged to conform to these parameters by using a more conductive metal(e.g., aluminum, silver, copper and their alloys), changing itsthickness and/or its width.

Many methods may be used to form highly conductive busbars which areformed around the substantial perimeter of the device, and severalmethods are given in U.S. Pat. No. 6,317,248 where a busbar is formed bywrapping a conductor from the front, onto the edge and finally wrappingaround the opposite surface. Substantial perimeter is defined as morethan 50% of the perimeter on each substrate. Conductive busbars may alsobe formed without wrapping over the back surface. For example these mayonly be limited on one surface or they may continue to be wrapped aroundthe adjacent edge.

For mirrors with third surface reflectors, it is preferred that a busbarbe economically formed on the transparent conductor covering more than50% perimeter, and more preferably 100% of the perimeter. One method todeposit high conductivity busbar on the substrate perimeter is bydepositing a silver frit. This process is described in detail in U.S.Pat. No. 6,317,248. Most silver frit processes need a firing temperaturein excess of 400° C. For those devices which utilize already formed ITOcoatings, it is preferred that the maximum firing temperatures be keptlower than 400° C. and preferably lower than 350° C. so that theconductivity and the optical properties of the ITO are not compromised.Thus those materials and processes are preferred which either melt below400° C. or are processable below 400° C. More preferably thistemperature should be below 350° C.

According to the present invention, busbars can be formed by sprayprocesses comprising of conductive particles with an organic binder maybe employed. The interior of the substrate may be masked or the coatingprocess may be such that only the local area for the busbar is coated.The organic binders polymerize or solidify on the substrate. Examples ofthis are Choshield™ and Choflex™ coatings from Chomerics (Woburn,Mass.). Another preferred way is to use a thermal or a plasma sprayprocess which only uses 100% metal. An example of this is a coating of atin/zinc alloy (and a process) available as EcoPlate™ 5030 fromChomerics. Thermal and plasma spray coatings from APS Materials Inc(Dayton, Ohio) may also be used to deposit a variety of metals, cermetsand conductive ceramics. This uses typically 80/20 tin/zinc alloy whereits surface resistivity is 0.005 ohms/square for a buildup of 25 micronthick layer. For this the busbar resistivity with a 30 cm length and 2mm wide strip would have a resistivity of 0.76 ohms. The melting pointof this material is 270° C. This material also has good corrosionresistance such as against salt water spray. Other materials comprisingof tin, zinc, aluminum and indium may also be used. Layer thickness forbusbar may be any, but the preferred range is from 5 to 50 microns.Since this is a spray process, the busbar may be optionally deposited sothat it wraps around the adjacent edge of the substrate to give higherconductivity. Ceramics may also be used as conductive busbars. Usuallythese comprise non-stoichiometric, usually reduced oxides, e.g.,TiO_(2-y), TiBr_(2-x). Where “x” and “y” are positive numbers usuallyless than 1 and show that these oxides are in a reduced state. One mayhave to use adhesion promotion layers between the transparent conductorsand the sprayed metals. These may be layers of metals such as chromiumand titanium which may be deposited by PVD and/or by electrolessdeposition or by electro deposition. The busbars may be wrapped from oneface of the substrate to the adjacent edge or it may continue to wraparound the opposite face as described in U.S. Pat. No. 6,317,248. Afterconnecting the busbars to connectors (via clips, solder or conductiveadhesive), they may be protected from scratching and handling, etc., bynon-conductive coating formed by any of the standard coating materials.Some of these coating materials are based on urethanes, acrylics, alkydsand epoxies.

Also, according to the present invention, rearview (or interior) mirrorsmay also be made using an alternative design that mimics the all aroundbus-bar. In this aspect of the present invention, a third surfacereflector/electrode is used with a front surface comprising of atransparent conductor (FIG. 14). This figure of an interior mirror doesnot show the perimeter sealant only to keep the figure unfettered fromconcepts not related to the discussion below. The substrate withtransparent conductor coating 145 is cut slightly larger (i.e. wider)along the long axis as compared to the reflective surface 146, so thatwhen it is assembled with the other substrate to form a cell, then alongthe substantial long axis of the device the transparent substrateprotrudes outward from both the sides 145 a and 145 b, so that a metalclip or a busbar may be attached to each side. This protrusion may alsobe optionally along one of the ends of the mirror (not shown). Whenseparate clips or busbars are attached to 145 a and 145 b, they arejoined together by wires to a common terminal or to separate terminals.The substrate with the metal reflector is cut so that it protrudes outon at least one of the ends of the mirror. This is where via a clip or asolder is attached. If it protrudes on both of the ends of the mirror(shown as 146 a and 146 b), one may attach a connector to both areas andthen pigtail them together to be connected to a common terminal or theconnector may only be attached to one end. The metal clip busbarattached to the transparent conductor is substantially attached to theentire lengths of 145 a and 145 b. For the reflective surface which ismuch higher in conductivity a short length of attached busbar in atleast one of 146 a and 146 b is sufficient. As long as the resistivityof the reflective coating (in ohms/sq) is lower than the transparentconductor by a factor of 10 or more, a uniformly coloring device isobtained. Thus one of the substrates (preferably the transparent frontsubstrate) has a busbar substantially around the perimeter (greater than50%), and the busbar (or other perimeter conductive connector) on theother substrate covers substantially less perimeter (less than 50%). Forpractical mirror devices the conductivity of the transparent coating onthe front surface is generally less than 200 ohms/square and that of thereflective conductor less than 10 ohms/square. For an exterior mirror asimilar concept may be used where the width and the height of the mirrorare similar. The transparent conductor may be powered from two parallelsides as discussed above, or it may be powered from almost around theperimeter, where the reflector below protrudes out at one or more of thecorners so as to attach the busbar.

This scheme of having one busbar (e.g. the busbar on the transparentfront substrate) substantially around (equal to or more than 50%perimeter) on only one of the two substrates (which form the cell)allows use of conventional busbar materials to get a benefit of allaround busbars for EC devices. This is particularly useful for 3^(rd)surface mirrors when the resistivity of the frontal transparentconductor limits the kinetic performance as described above. Theusefulness of this concept in providing a uniformly coloring andbleaching mirror depends on the width of the device and the surfaceresistivity of the transparent conductor. A simple rule where thisconcept of busbars may be used is when the width (measured in cm) of thedevice multiplied by surface resistivity (measured in ohms/square fortransparent conductor) exceeds 100, and more preferably 120. The widthis measured as the maximum width of the active area where the twobusbars are separated. For example in FIG. 14, width is the distancebetween the two arrows (147 a and 147 b) discounting the width occupiedby the busbars and the seal holding the two substrates. For an interiormirror with a width of 5.5 cm and using a front substrate with atransparent conductor coating of a resistivity of 45 ohms/square wouldbenefit from this arrangement as the multiplication of the two numbersexceeds 120.

This arrangement of all around busbar may be used even in third surfacemirrors where the transparent conductor has higher conductivity (e.g.between 5 to 25 ohms/square). This scheme may be particularly effectivein increasing the bleach speed of the self-erasable EC mirrors availablecommercially at present. This could be particularly important attemperatures lower than room temperature. The self erasable mirrorsbleach by back reaction when the powering voltage is removed or the twoterminals shorted. The electrolyte thickness is an important variabledetermining the back reaction. A lower electrolyte thickness leads tohigher back reaction and hence faster bleach. Too high back reactioninterferes with the degree of coloration as it leads to higher potentialdrop within the device and in extreme cases may lead to non-uniformcoloration where the color is deeper closer to the busbars at the edgesand lighter as one moves away from them. Thus the electrolyte thicknessis chosen to give the right balance between coloration and bleach. Theback reaction is typically measured by looking at the leakage current(or the steady state current) when the mirror reaches a steadycoloration stage at a given color potential. When the transparentconductor is powered from all around, a higher leakage current may besustained without loosing the coloration or color uniformity. Thus forthese devices the electrolyte thickness can be reduced to achieve higherbleach rate. This concept of all around busbars may also be extended for4^(th) surface mirrors (See FIG. 5), where transparent conductors areused as both electrodes, and one of these has a higher conductivity ascompared to the other. The transparent conductor that is more conductivehas busbars in less than 50% of the perimeter, and the side with lowerconductivity transparent conductor has busbars on more than 50% of theperimeter. As shown in FIG. 5, the reflective coating is placed on thefourth surface.

Substrates, Added Functionality Coatings for EC Mirrors

The first surface of the mirror device (see FIG. 5a ) which faces theuser, may also be coated to impart further functionality. These could becoated with self-cleaning coatings which may be hydrophilic, hydrophobicor have catalytic properties activated by light. The hydrophilic coatingkeeps the vision clear during fog or rain, as water spreads over thesurface in a uniform transparent film. In the hydrophobic coating waterbeads up and flows away thus keeping the vision clear. Any of thesecoatings may be used. For hydrophilic coatings it is preferred that thecontact angle of water with the coated surface at 25° C., 50% humiditybe below 20 degrees. For hydrophobic coating the contact angle undersimilar conditions of testing should be preferably greater than 100degrees. The light activated coatings are typically comprised ofsemiconductor oxides such as titania (see U.S. Pat. No. 5,595,813). Forhigh transparency it is preferred that they have an optical band gapbelow 400 nm. A preferred titania coating comprises micro ornano-crystals of anatase phase. These coatings generate photo-activatedspecies that can oxidize surface organic impurities and keep thesurfaces clean. Multiple layer hydrophilic coatings for use inautomotive EC mirrors are described in U.S. Pat. No. 6,447,123 and in WO03/012540. The outside surfaces may also be coated with high or lowindex materials relative to the substrate to increase or decrease thereflection. These could also be multiple coatings stacks so as to reducereflections by destructive interference. Some of these coatings may becombined (e.g., multiple stacks) to result in more than onefunctionality (such as catalytic activity to oxidize surface impuritiescombined with hydrophillicity). Inexpensive self-cleaning coatings oftitania are deposited by pyrolytic process on glass (see U.S. Pat. No.6,027,766). Before the deposition of these coatings it is typical todeposit a coating which acts as a barrier coat to stop sodium ionsdiffusing in the photo-active coating and poisoning its catalyticactivity. Catalytic coatings with underlying coatings for barrier coathave not been used for automotive mirrors before. A more preferred andeconomical route for EC devices which use active coatings is to useglass which has these coatings deposited on one of the surfaces bypyrolytic process. For mirror applications the haze of the coated glassshould be below 1%. Care should be taken that this coating does not getirreversibly contaminated or damaged during subsequent processing. Thetransparent conductor for use in EC device is then deposited on thesurface which does not have the active coating and then employed to makethe EC device. For EC automotive mirrors only the front substrate needsto constructed in this manner. The use of glass with barrier coatresults in an active coating that lasts for a long time for use inautomotive conditions, and in addition, pyrolytic coatings are harderand more durable as compared to coatings deposited by other processes.Self cleaning glass is available under the trade name of Active™(Pilkington, Toledo, Ohio) and Sunclean™ (PPG, Pittsburgh, Pa.). Rearview mirrors comprising ionic liquids in the electrolyte may beintegrated in an automotive system with a heater in a similar fashion asconventional electrochromic mirrors. This heater primarily functions toremove frost or dew deposited on the mirror surface. Advantageously, italso overcomes the sluggish response of the EC devices at lowtemperatures if the mobility of the dyes reduces. For example these canbe heated using a heater pad from behind or even imprinting a resistiveheater pad on the back of the mirror, e.g., as given for electroopticmirrors in U.S. Pat. No. 5,808,777 and U.S. Pat. No. 4,584,461. This canbe implemented for automotive interior or exterior mirrors, however, theaddition of a heater is more common for exterior mirrors. The heater maybe self-regulating in terms of the highest temperature as would be incase of a resistive pad utilizing positive thermal coefficient (PTC)mechanism. Information on this can be found from Dupont'sMicroelectronic materials division (Wilmington, Del.). As an example PTCheaters may be made by depositing polymeric coatings loaded with carbonparticles on polymeric sheets such as polyethyleneterephthalate. Theheater can be activated when the temperature falls below a certainvalue, e.g., below 20° C., or it may always be activated to keep themirror temperature between 40 and 50° C. This will ensure that themirror kinetics is always similar regardless of the ambient temperaturein the mirror vicinity.

Low weight EC devices could be made using ionic liquids. As an example,for automotive mirrors, the substrate thickness could be in the range of2.5 mm down to 0.5 mm. The two substrates used for making the cavity forthe devices need not be the same thickness, they may even have differenttransparent conductors, e.g., one may be ITO coated and the other tinoxide coated such as TEC glass from Pilkington (Toledo, Ohio), or one ofthem may have a metallic conductor as described above. Thin substrateshave also been used in EC mirrors (generally less than 1.5 mm inthickness). Further, the use of thin substrates has an advantage innon-planar mirrors. If mirrors such as convex or multi-radius arerequired (e.g., combination of flat and curved regions in the samemirror to eliminate blind spot (e.g. see U.S. Pat. No. 6,522,451), it iseasy to bend thin substrates without causing creases andnon-uniformities. Thin substrates as described in U.S. Pat. No.6,195,194 may also be used in this invention.

Also, use of preferred ionic liquids lends itself more favorably to theuse of plastic substrates in electrooptic devices as these liquids areinert towards a large number of commercial polymers. Plastic substratesresult in low weight and also better impact resistance. An additionaladvantage of using the ionic liquids is further protection of automotiveinteriors. In case of a mirror breakage or leakage, the electrolytewould not interact and blemish the interior plastic components such asdashboard. Further, if EC mirrors are made with plastic substrate in therear and glass substrate in front, issues related to scratch resistanceare avoided. When the back substrate is made of a plastic material thena metal coating or a stack comprising of a metal layer is deposited toact both as a reflector and as one of the two conductors in the EC cellcavity. U.S. Pat. No. 6,193,379 describes the use of cyclo-olefins aspreferred material for use in EC devices, particularly EC mirrors. Wehave determined that it is not sufficient for EC devices, particularlyautomotive mirrors and windows to have substrates made only fromcyclo-olefins without meeting some specific thermal criteria. It isimportant for these polymers to have good dimensional stability,particularly against temperature and moisture uptake. This reduces theissues related to dimensional stability such as stress on seals, warpingand keeps the image quality high. In many constructions glass may stillbe used as the front substrate, thus it is important for the rearsubstrate to have low expansion to reduce warping with change intemperature. Thus, crystalline polymers are preferred as they have lowerexpansion. Amorphous polymers with high Tg may be used as long as Tg ishigher than any of the processing, testing or use temperatures. It ispreferred that amorphous thermoplastic polymers have Tg in excess of120° C. (as measured by differential scanning calorimeter at 10° C./minheating rate) and moisture absorption less than 0.1% (as measured byASTM D570). Thermoplastic crystalline polymers or thermoset polymersmust have heat deflection temperature (HDT) greater than 100° C. andmoisture absorption of less than 1%, and preferably less than 0.1%. HDTis measured according to ASTM D648 at 0.45 or at 1.8 Mpa. Thermalexpansion may also be reduced by adding mineral fillers and/or glass tothe polymers. Linear thermal expansion coefficient of preferred mineralfillers and glasses should be less than 10⁻⁵/° C. in the range of −40 to120° C. These fillers may be typically present in a range of 10% andmore preferably 50% by weight. The fillers may also be nano-particles,e.g., surface treated inorganic clays described in the sealants section.These fillers are effective in terms of imparting superior barrieragainst fire and moisture and or gas diffusion. Filled plastics mayemploy additives which result in high surface finish. These additivesmay be other low viscosity polymeric materials which during processingmigrate to the surface.

Some grades of cyclo-olefins that have high Tg are Topas 6013, 6015,5013 and 6017 from Ticona (Summit, N.J.) and Zeonex RS820 (Zeon, Tokyo,Japan). Generally, high temperature resistant polymers such aspolyarylates, polysulfones, aromatic polyesters, polyphenylene oxide,polyketones, polyether ketones and their blends will also be suitable.The polymers may also have inorganic fillers. Some of these may becolored or opaque, but they will be still suitable for back substratesin mirrors if they are metallized for use as one of the electrodes. Forthe back substrate that does not have to be transparent a low costoption is the use of engineering polymers such as acetal polymer (e.g.,Celcon® MT8U01 and M15Hp from Ticona) where electrode conductivity andreflectivity is provided by a metal coating. Substrates (flat or curved)are preferably molded from thermoplastic or thermoset polymers.Alternatively, these may also be cut from extruded sheets which may becurved by thermoforming. Some examples of thermoset polymers are sheetmolding compounds (SMC) and bulk molding compounds (BMC) usedextensively for class “A” finish on automotive panels. These may befurther treated with moisture and/or oxygen barrier coatings. Thesepolymers may even have oxygen scavenger additives, e.g., Amosorb™ fromBP Amoco Chemical Co (Chicago, Ill.), which are typically added in aconcentration range of less than 2%. Some polymers may require tielayers to ensure good adhesion of the metallic coatings on to them. Thetie layers may be inorganic, organic or may be a surface modification,e.g. as discussed earlier in the section “EC mirror electrodes andmethods to deposit them”. The inorganic tie layers may be metal oxidesor a different metal. Some examples of organic tie layers forpolyolefins are maleic anhydride grafted polyolefins and acrylates, andsilane coupling agents. Grafted polymers for improving adhesion areavailable under the trade name of Amplify™ from Dow Chemical (Midland,Mich.). Surface modification for improving adhesion may also be done byvariety of treatments such as plasma treatment, corona treatment, flametreatment, treatment with strong acids and/or bases.

Further, high moisture absorption prone polymers may be used aftermoisture barrier treatments. These polymers may be treated withadditional layers to give an oxygen barrier as described in U.S. Pat.No. 6,193,379. Incorporation of additional layers increases the productcost. When pin hole free metallic coatings or oxide coatings (such astransparent conductors) are deposited which are either one of conductoror a reflector in the device these will form a good oxygen barrier, thusavoiding the need for additional barriers. However, with electrolytescomprising of preferred ionic liquids, moisture is less of an issue.

Sealants and Sealing of Devices

The sealing of EC devices can be done using several methods. Generallyfor liquid electrolytes a cell cavity is fabricated by depositing anadhesive along the perimeter of one of the substrates. Spacer beads areadded to the adhesive and/or sprinkled on the substrate. The secondsubstrate is lowered onto the first one and clamped and then theadhesive is cured yielding a hollow cavity or chamber. To fill thecavity with a fluid at least one gap is left in the sealant or at leastone hole is made into one of the substrates. The cavity is filled usingthis gap or hole and then this is plugged with another adhesive, a solidplug or combinations thereof. The adhesives may be radiation (e.g., UV)and/or heat cured. In those cases where the electrolyte is preformed asa solid sheet, the electrolytic sheet is lowered onto one of thesubstrates but kept clear of the peripheral regions. An adhesive bead isput around the electrolytic sheet and the second substrate is loweredonto the first substrate sandwiching the electrolyte and the adhesivebead. This is then laminated to both cure the adhesive and bond theelectrolyte to the substrates. Alternatively, one may laminate theelectrolyte between the two substrates and then apply an edge sealant.

Spacer beads may be made out of a variety of inorganic and organicmaterials. These may be glasses or crystalline materials. Some choicesin non-conductive inorganic materials are various crystalline mineralssuch as alumina, zirconia, titania, silica and tantala beads, andglasses such as compositions based on soda-lime and borosilicate, etc.Hollow beads, or those materials which expand during processing (such asseal curing at elevated temperature) may also be used. Hollow beads madeout of glass (Scotchlite™ glass bubbles) and from ceramics (Zeeospheres™and Z-Light™ microspheres) are available from 3M (Minneapolis, Minn.)and expandable beads are available from Expancel (Duluth, Ga.). When themirror size gets bigger, typically if the minimum average distancebetween the opposite side of the sealant starts exceeding 7.5 cm, onemay use beads which are sprinkled on to the interior of the cavityformed by the two substrates. Spacers may also be added to the interiorof those devices where the substrates are curved, such as non-planerautomotive mirrors or those devices that use thin substrates (e.g. lessthan 1.5 mm) or those which are less rigid (e.g. which have a Young'smodulus of less than 2 million psi). This may be done while spacers areadded to the edge sealant. It is preferred that the spacers which areadded within the cavity are of a refractive index similar to that of theelectrolyte. Alternatively these spacers may also be solubilized ordispersed in the electrolyte matrix. Once the edge sealant is cured andthe cell filled with the electrolyte, the cavity spacing is generallymaintained. Beads made from polymers which were described earlier forsolidification of electrolyte by forming two phase systems, or used forviscosity modification may be used for this purpose.

U.S. Pat. No. 5,233,461 describes the use of organic thermoplasticsealants. Typically these sealants are cut as perimeter gaskets fromthin sheets of a thermoplastic polymer which is then laminated betweenthe two substrates using heat and pressure. An example of thermoplasticedge sealant is Surlyn™ ionomer (from Dupont, Wilmington, Del.). Sheetsof thermosetting adhesives can also be used in a similar fashion.Examples of these sheets are available from 3M (Minneapolis, Minn.) asstructural bonding tapes (e.g. number 9244).

The peripheral area of the EC cell forming substrates may be primed toimprove its adhesion with the sealant. Alternatively, adhesion promotersmay be added to the sealant itself. The adhesion promoter in the primeror the one added to the sealant must be compatible both with thesubstrate and with the sealant. Typically the adhesion promotermolecules (also called coupling agents) where one end reacts or bondswith the substrate and the other end reacts or bonds with the sealantare preferred. This is known in the art, and as an example silanes arethe most commonly used adhesion promoters for glass, metals and metaloxide surfaces. A good reference for such issues including primerformulations is “Silane Coupling Agents” by Edwin P. Plueddemann, PlenumPress 1991. Non-silanes such as zirconates, titanates and aluminates areavailable from Kenrich Petrochemicals (Bayonne, N.J.). Typical silanecoupling agents for use with epoxy adhesives have one end which isreactive or compatible with the epoxy resins, some examples of thereactive ends are epoxy, mercaptans and amines. Specific examples ofthese from Dow Corning (Midland, Mich.) are Z6020 (amine) and Z6040(epoxy); Silquest A-189 is a mercaptan silane from Witco (SouthCharleston, W. Va.). For acrylic adhesives including those which are UVcured a methacryloxy functionalized silane is preferred, e.g., A-174from Witco. More details on surface treatments, primers, adhesionpromoters and adhesives can be found in “Handbook of Adhesives &Sealants” (Edward M. Petrie, McGraw Hill (1999)). Some application notescan also be found in PCT application WO 00/17702. These silanes may alsobe added to sealants prior to dispensing so that a separate step ofpriming is avoided. These primerless sealants may be used for use inelectrooptic devices. Generally when these are added to the sealantsdirectly, their percentage by weight is usually lower than 10% of thetotal sealant, and preferably lower than 2%. According to thisinvention, improved primerless adhesives may be prepared by addingpre-hydrolyzed silanes to the sealants. These sealants have goodenvironmental resistance. Pre-hydrolysis of silanes is typically done byadding acidified water (preferred pH between 2 and 4). The amount ofwater added should be sufficient to hydrolyze on an average 0.1 to allthe alkoxy groups, and the preferred range being 0.5 to 2 of the alkoxygroups. These are then mixed for a period for hydrolysis to take placebefore adding them to the resin (sealant). The period for hydrolysis maybe from several minutes to many days and is dependent on the pH,temperature and the quantity of water added. The hydrolysis reaction maybe carried out at room temperature or at elevated temperature.

From a durability perspective and in order to pass qualification tests(listed below), a seal with high Tg (glass transition temperature) ispreferred. Tg may be measured by differential scanning calorimeter at aheating rate of 10° C./minute, and preferably it should be greater than120° C. and more preferably greater than 130° C. and most preferablygreater than 140° C. High Tg ensures that the permeability to oxygen andwater vapor is low and that the devices are able to pass elevatedtemperature and/or humidity tests without warping or causing excessiveexpansion at the adhesive joints. For example U.S. Pat. No. 6,245,262lists tests for automotive mirrors. These tests may also be used fortesting devices for other applications. These tests are: 96 hours orlonger in boiling water, 720 hours or longer at 85° C./85% RH and asteam autoclave test at 121° C. (15-18 psi) for 144 hours or longer. Ofthese the autoclave test is considered to be most challenging. It maynot be necessary that the Tg of the adhesive needs to be higher than thetest temperature to pass the tests, but it is preferred this way so thatthe diffusion of elements such as water and oxygen into the device iskept low during these tests.

From a processability perspective, it is desirable to use sealants whichhave a long pot life. The long pot life ensures consistency inmanufacturing and less interruption as the viscosity change over aperiod of time is lower. These sealants may be formulated in onelocation and may be transported to other locations without usingexpensive refrigeration techniques. Epoxy resins which are cured usinglatent curing agents will result in long pot life. Use of latent curingagents for sealing EC devices is described in U.S. Pat. No. 5,724,187.In this patent those epoxies are described which are bifunctional andcured with latent curing agents. These types of epoxies only result inlow Tg (generally lower than 100° C.) and the resulting devices do notstand well to elevated temperatures or elevated temperature testing suchas autoclave testing for automotive mirrors. The pot life at 25° C. roomtemperature of the formulations with latent curatives should exceed 12hours, preferably 7 days and most preferably 4 weeks. Latent curingadhesive in U.S. Pat. No. 5,724,187 discusses in detail using Epon 8281(from Resolution Performance Products, Houston, Tex.) and Ancamine 2014G(From Air Products, Allentown, Pa.) for automotive mirrors. According tothe product brochure from Air Products this material in cured state hasa Tg of only 110° C. Further, the most preferred sealants are those witha glass transition temperature of less than 100° C. PN23 (From AjinomotoCo, Inc, Paramus, N.J.) as a latent curing agent is listed but it is notpreferred as it has a higher Tg. This patent had a list of many curingagents with long shelf lives, but no data was given to demonstrate ifthese passed the tests. U.S. Pat. No. 6,195,193 discusses curing epoxyDEN 431 (from Dow Chemical, Midland, Mich.) with Ancamine 2049 (from AirProducts). The pot life of the curing agent in the product brochure withbifunctional epoxy is listed as 400 minutes and period in which theresin may be processed would be even shorter. Thus when it is used witha higher functionality epoxy such as DEN 431, the pot life will be stillshorter.

We have determined that most desirable combination of properties for thesealant is long pot life, high Tg and good barrier for moisture andoxygen and sustain the above tests, in particular, the autoclave test.Expansion coefficient for bonding glass substrates may also be an issuewhich is typically reduced in organic adhesives to match glass by addinginorganic additives. The inorganic additive content may be low (lowerthan 30%) if nano-particles comprise the inorganic additive package.When no nano-particles are used then the inorganic content shouldpreferably be greater than 30% and more preferably greater than 35%. Aswill be discussed later preferred adhesives of this invention employanhydride curing agents. Examples of latent curing agents are Ancamine™2014, 2441 and 2442 from Air Products (Allentown, Pa.). All of thesematerials are solid at room temperature. However, when these are curedwith Bisphenol A type epoxy (e.g., Epon 828 and 8281 from ResolutionPerformance Polymers (Houston, Tex.) and DER 331 from Dow Chemical Co(Midland, Mich.) result in Tg's lower than 120° C. Higher latency canalso be achieved by using dicyandiamide (DICY) curing agents, e.g.,Amicure™ CG-NA, CG-325, CG-120-0, CG-1400 and Dicyanex 200-X from AirProducts. DICY curing agents are solid at room temperature. The use ofDICY with Bisphenol A epoxies listed above results in a desirable glasstransition range. Mixed curing agents can also be used such as a mixtureof Ancamines described above and the DICY curing agents. The use ofthese materials, their proportions and curing conditions are describedin product literature from Air Products. Other accelerators can also beused for DICY, e.g., imidazoles, examples of these are sold under thetrade name of Curezol and Imicure from Air Products. The preferredimidazoles are Curezol 1B2MZ, Curezol 2E4MZ, Curezol 2MA-OK, Curezol2MZ-Azine, Curezol 2PHZ-S, Curezol 2PZ, Curezol 2P4MZ, Imicure EMI24 andImicure Imidazole. The more preferred of the imidazoles are solidpowders at room temperature, which are Curezol 2MA-OK, Curezol2MZ-Azine, Curezol 2PHZ-S, Curezol 2PZ, Curezol 2P4MZ and ImicureImidazole. These imidazoles may also be used as catalysts for latentformulations when epoxies are cured using anhydrides. Yet otheraccelerators for DICY are substituted ureas, e.g., Amicure UR, AmicureUR-S and Amicure UR2T from Air products. Many of the above mentionedimidazoles may also be used as sole curing agents. Solid latent curingagents may also be purchased from Ajinomoto Co, Inc (Paramus, N.J.)under the trade name of Ajicure PN-23, PN-H, PN-31, PN-40, PN-23J,PN-31J, PN-40J, MY-24 and MY-H. The PN is typically used with DICYcuring agents and the MY series with anhydrides or either of them may beused as sole curing agents. DICY and latent curatives have also beenmixed in a single package, e.g., AH-154 and AH-162.

The use of latent curing agents which result in high Tg's, and arefilled with nano-particles or have high inorganic content, and whichpass the autoclave test are novel for electrooptic devices, and inparticular EC and EL devices. Using Ancamine latent curing agents assole curing agents, Tg may be increased by using higher functionalepoxies such as those based on Novolac e.g., EPON Resin 160, EPON SU3and EPON SU2.5 (from Resolution Performance Products, Houston, Tex.),DEN 431, DEN 438 (from Dow Chemical in Midland, Mich.)) and THPE-GE fromDupont Electronic Technologies (Danville, Calif.). The higherfunctionality resins may also be mixed with bifunctional epoxies, e.g.,THPE-GE and EPON SU3 is preferably mixed in a proportion of less than25% by weight in a bifunctional epoxy such as EPON 828 or EPON 8281.Multi-functional epoxy resin for the purpose of this invention of theresin is defined as the average number of reactive (epoxy) groupsgreater than 2. A mixed resin with an average functionality greater than2 would be considered multi-functional for this invention. A desiredcuring temperature is in the range of 100° C. to 200° C., and morepreferably between 120° C. and 150° C. The curing time may vary fromseveral minutes to several hours. All sealants of this invention mayalso be cured using microwaves, which may be optionally followed orcured at the same time by thermal curing. Microwave and or thermalcuring may also be assisted by other forms of radiative curing such asinfra-red. Typical fixed microwave frequencies which may be used are 215MHz, 434 MHz and 2.45 GHz. Variable microwave frequencies (in the rangeof 100 MHz to several GHz) may also be used, and they may be tunedaround a particular frequency to increase the absorption of themicrowaves. The tuned frequency is dependent on the material compositionincluding additives. At these temperatures the solid curing agents mustmelt and react. Typically the latent curing agents or accelerators areground to a fine solid powder (usually less than 20 microns in size andmore preferably less than 10 microns in size) and mixed with the liquidepoxies. These have poor solubility in the epoxy liquid resins at roomtemperature and this promotes the latency. During cure cycle, atelevated temperature, these melt and become soluble and more reactive.Another way of increasing latency while using bifunctional or higherfunctionality epoxies is by using these curing agents as catalysts forepoxy/anhydride reactions. Anhydride curing agents are generally lowviscosity liquids, thus it is easy to add higher inorganic contents asthey can be easily wetted and mixed well in the sealant. Those anhydridecured sealants which result in Tg of more than 120° C. are preferred.The above-mentioned Ancamine latent curing agents and those fromAjinomoto Inc may also be used to accelerate those reactions where thecuring is done by anhydrides. Some examples of liquid anhydrides arenadicmethyl anhydride, methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride. Low flammability characteristics to theseals may be imparted by using halogenated seals. A part or all of theepoxy resin may be substituted by a brominated epoxy resin (e.g., DER530-A80 from Dow Chemicals). More UV stable epoxy resins which result inhigh Tg are cycloaliphatic resins such as Cyracure 6105 and 6110 fromUnion Carbide (Danbury, Conn.). High Tg may also be obtained by curingbifunctional epoxies such as EPON 828 and DER 331 with PN-23. Typicallythe shelf life of anhydride cured epoxies utilizing MY-24 and MY-Hcatalysts is superior.

The adhesives may also comprise colorants (e.g., non-conductive carbonblack), viscosity control additives (e.g., Fumed silica, such asCab-O-Sil™ TS 720 from Cabot Corp), mineral fillers (e.g. calciumcarbonate and silicates) coupling agents, oxygen scavengers and spacerbeads. Oxygen scavengers are described in the substrate section.Commercial fumed silicas are amorphous. The mineral fillers shouldpreferably be coated with coupling agents such as amino and epoxysilanes for use in epoxy adhesives. The size of the fillers should besmaller than the spacer beads. It is preferred that the formulated epoxymix should be thixotropic and/or have a viscosity higher than 100P orpreferably higher than 1000P. This keeps all the fillers and/or solidcuring agents suspended in the formulated epoxy mix and also providescontrol of flow, so that when the substrates are mated with the epoxysandwiched between the two the quality of the adhesive lines are smoothand of the desired width. This width is usually dependent on theapplication and may be as wide as one cm to about 3 mm for large windowsand is about between 1 to 6 mm for automotive rear-view mirrors.

Epoxy resins may also be stabilized against UV degradation by adding UVstabilizers, crystalline nanoparticles of metal oxides. UV stability isneeded when the sealant may be exposed to the elements, especially forthose mirrors where flush look is required rather than a molded bezel tocover the perimeter. Many of these additives may be added together. Someexamples of UV stabilizers are UVINUL 3000 (from BASF, Parsippany,N.J.), Tinuvin 213 and Tinuvin 770 (from CIBA Specialty Chemicals, WhitePlains, N.Y.). Examples of nano-particle sized oxides, which block UV,are titanium oxide, cerium oxide, copper oxide and zinc oxide.Nano-particles for seals should have at least one dimension smaller than100 nm. As an example titanium oxide particles may be purchased fromDupont (Wilmington, Del.) under the trade name of Ti-Pure R960. A sourceof several metal oxides is Nanophase Technologies (Romeoville, Ill.)available under the trade name of NanoTek™ and from NanoProducts(Longmont, Colo.). Typically the addition of the UV stabilizers is below20% by weight of the weight of the epoxy resin in the formulation. Theseseals may be clear, colored or opaque. Typically the colors areconsidered dark when their colors expressed on a L*a*b* scale, and thevalue of L* is less than 30. It is preferred that these seals have avalue of L* of less than 60 where an L* value above 45 is consideredlight coloration. It is also preferred that these seals be opaque ordiffuse scattering. This is so that in the darkened state of the mirror,specular reflections from these areas is negligible if it is in theviewer's vision. The scattering as measured by haze value shouldpreferably be greater than 20% and preferably greater than 30%. Haze maybe measured by bonding two transparent substrates with an adhesive filmof the same thickness, which would be used in the application, usingASTM D1003. Haze values greater than 30% is considered diffusing and maybe measured using ASTM E167.

Crystalline nano-particles have other advantages as well. These canprovide shrinkage control in curing, high barrier properties fordiffusion of electrolyte, water, air, etc., increased Tg and also flameretardance (Wang, Z., Massam, J., Pinnavaia, T. J., “Epoxy ClayNano-composites” in Polymer-Clay Nanocomposites, Pinnavaia, T. J.,Beall, G. W., editors, Wiley, New York, 2000). Some specific examples ofnano-particle clays from Nanomer® from Nanocor (Arlington Heights,Ill.); surface treated talcs from Argonne National Laboratory (Argonne,Ill.) and Geramite® and Cloisite® from Southern Clay Products (Gonzales,Tex.). These are crystalline inorganic clays with plate like structures,and the Nanocor®, Geramite® and Cloisite®, materials are based onmontmorillonite mineral. Typically the clays are surface modified toreplace sodium ions by alkylammonium ions so that they are compatiblewith the organic resins and are able to exfoliate in to thin flakes. Thethickness of these clays is generally about 1 nm (for completelyexfoliated mineral) and their width and length are usually less than1000 nm. These are typically used in a range of 2 to 50 percent byweight of the resin including curing agent. For example a grade moresuitable for use with epoxy materials are Nanomer® I.28E Nanomer® I.30Eand Cliosite30B. Nanomer® I.28E is a onium surface modified mineral andalso suitable for anhydride cured epoxies. The sealants may alsocomprise nanoparticles comprising silsesquioxanes to impart many of theproperties which are also imparted by nano-clays discussed above. Theseare nanoparticles on a scale of large molecules and include inorganiccages (generally of silicon oxide) with surface groups which arereactive or compatible with organic resins. These are available forincorporation in sealants as Polyhedral Oligomeric Silsesquioxanes(POSS) from Hybrid Plastics (Fountain Valley, Calif.). As an example aPOSS material for incorporation in epoxy resins is EPO408. These POSSmaterials may be substituted for the clays or may be added along withthem. A typical concentration range is less than 5% by weight of theresin and preferably less than 2%. These materials may be used withother ingredients described above including other mineral fillers,colorants, fumed silica, etc. These additives may also be incorporatedin plug seals (for plugging the fill hole) which are typically cured byradiation such as UV.

The area where the clip busbars are attached to the electrodes may alsobe sealed after the attachment of the busbars. This prevents moistureingress in this area and also keeps the busbars mechanically tiedagainst vibrations etc during product's use. Usually the sealants arelow viscosity materials, generally lacquers, paints and solgel coatingswhich may flow around the clip. Prior to the application of thesematerials a coating of adhesion promoters may be applied, such as silanebased primers discussed above, e.g. amino silanes may be used forepoxies and urethane based sealants. These sealants may be epoxies,urethanes, silicones and alkyd resins which may be thermally cured orcured by radiation. These may be flexible or rigid, and as an examplemay be comprised of epoxy compositions which were discussed for the mainsealant. Their viscosities for application may be lowered by reducinginorganic fillers, or adding extractable solvents. Silicones andurethanes may also be room temperature vulcanizing (RTV) type where thematerials cure by interaction with ambient moisture. Another class ofmaterials suitable for this are hot glues, including those which afterdispensing provide immediate handling strength upon cooling and thencontinue to cure or cross-link with time as they interact with ambientmoisture, UV radiation, or due to a reaction with a material present onthe surface (e.g. included in the primer) which activates the curingreaction. An example of hot glues which cross-link after dispensing areJet-Weld® adhesives from 3M (Saint Paul, Minn.), a preferred adhesivefrom this class is TS-230.

Displays and Indicators for Mirrors

Active Display in EC Mirrors

Displays are typically provided in EC mirrors for conveying additionalinformation (U.S. Pat. No. 4,882,565). Active displays in this contextare those which are either capable of changing the information beingdisplayed or they may be turned-off or turned-on. These displays may bein the mirror casing or in the mirror area. In interior mirrors thedisplay may provide information on direction where the vehicle is headed(compass), amount of gas remaining, tire pressure, inside and/or outsidetemperature, internet communicated information, any warning or statussignals such as open door, safety bag, etc. The displays in the outsidemirror may provide blind spot information for the driver, or the turnsignals for those cars in the vicinity of the vehicle withoutdistracting the driver, directions from a GPS system and so forth. Thefeatures described below are applicable to all mirrors made byelectrolytes comprising of ionic liquids.

When these signals are provided in the mirror area, the display istypically placed behind the mirror. For a fourth surface mirror a smallarea is cleared of the mirror to which the display is affixed with atransparent adhesive. Alternatively there may be pin holes in thereflector or it may be partially transparent so that a display locatedin the back may be seen through the layer when it is activated. Thedisplays as described in prior art, are generally fluorescent, inorganicLED's, organic or liquid crystal types. However, none of these describedisplays which are formed on one of the substrates, or formed on aflexible film and bonded onto them.

For third surface mirrors, where the reflector and one of the electrodesare the same, there are other methods for providing an opticallytransmissive window while still keeping the conductivity in that area.One method is to use a transparent conductor coating on or below thereflective layer. In either case during the reflective layer depositiona small area is masked for the display or it is removed from this areaafter deposition. In yet another method, the reflective layer is madepartially transmissive by controlling its thickness so that a brightdisplay on the back of the mirror is visible (U.S. Pat. Nos. 5,724,187;6,512,624; 6,356,376; 6,166,848). This partial transmissivity may be forall of the reflector or only in the window area. Yet another method isto remove the reflector partially so that part of the reflector is leftas fine conducting lines which bridge with the continuous part of thereflective layer (U.S. Pat. No. 5,825,527) so that the area for thedisplay is substantially devoid of the reflective conductor. This iscreated by removing the reflective coating by a laser which is moved inseveral lines in that area. The non-conductive areas between the linesare about 0.005 inches wide. This process is expensive, as the laser hasto be moved linearly to cover the entire area. In addition the residualreflector lines may not be visually appealing for some displays. Thewidth of the lines should be less then 0.005 inches for most automotivemirrors as discussed below. These lines may be parallel with similarwidth and spacing, or they may also have variations to avoid any opticalinterference effects. These may also be a set of lines running indifferent directions giving rise to a mesh.

In one preferred method the reflector is removed (or not deposited) fromthe display area completely, and conductive lines (or a mesh) isdeposited by a separate process in this area to bridge the conductivereflector on its perimeter. This can be processed by either depositingthese lines (or mesh) prior to the deposition of the reflector layer orafter the reflector layer deposition. The width of the lines (or thelines forming the mesh) should be so chosen so that these are invisibleto the eye. Typically, the eye is unable to see lines which subtend anangle of about 0.01 degrees or less. This means depending on the averagedistance between an occupant and the mirror, the line width can becalculated. For example a mirror located at 45 cm from the eye of adriver, the line width at 0.01 degrees corresponds to 79 microns.Depending on the mirror distance this number would vary. For the purposeof this invention a preferred subtended angle is less than 0.015degrees. Thus any width given by this calculation which is difficult todiscern by the eye or less than 125 microns width is preferred. Toensure that these lines are invisible, it is preferred that the distanceused is an average from the eyes of a driver or a passenger, whosoeveris closer. The conductors used to form these lines may be reflective orabsorptive and may appear as translucent, opaque, dark or even diffuselyscattering. Since the visibility of these lines is kept to a minimum,their optical properties are not that important. The line spacing may besimilar to the line width or different. These lines may be silk-screenedeconomically using silver paste or other conductors. These are availablefrom Dupont Electronic Materials (DEM) as Silver Thick Film Compositions1991, 1992, 1993, 1997, 7713 and Solamet Photovoltaic composition asE64885-52A and from Ferro Inc (Santa Barbara, Calif.) as FX 33-246.These may also be platinum and gold bearing conductors and inks from DEMand Englehard Electronic Materials (East Newark, N.J.). Engelhard alsouses inks in organic media comprising of platinum and silver particles.These may also be made out of coating materials from Chomerics describedearlier or may be conductive adhesives with silver, silver alloy ornickel particles. Formulations containing inherently conductive polymersmay also be used as long as these are inert from an electrochemicalperspective in the voltage range of mirror operation. These lines mayalso be formed using micro-photolithography using Fodel materials andprocess (or equivalent) from Dupont. Some Fodel photoprintableconductors are DC 201 and DC010.

In another novel concept of the present invention, these lines orpatterns may be preformed and prepared as individual patches on areleasable tape. A z-axis conductive adhesive is applied on to this andthen a bottom release layer is applied to encapsulate this. In themirror assembly, this patch is placed over this area after removing thebottom release layer. After the patch is affixed (either pressuresensitive adhesion and/or followed by curing), the releasable tape isremoved thus exposing the conductors. Particularly in this invention useof acrylic adhesives inside the device may be acceptable as the ionicliquid comprising electrolytes will not degrade or plasticize them. Inany of these the total thickness of the lines and adhesives should beless than the electrolyte thickness. Further, in some cases it may bepreferred to match the appearance of the lines (color and reflectivity)to that of the mirror.

When emissive displays are used in the mirrors it is preferred that thecolor of the display (or its emission color) is similar to the mirror inthe colored state. As an example a green color display is preferred ifthe mirror turns green when activated. This keeps the brightness of thedisplay less affected even when the mirror dims. In other words theemission characteristics of the display should preferably be matched tothe optical region where the mirror transmission is maximum in thecolored state. Thus this simple scheme may not require sophisticatedcontrol of the display intensity with changing mirror transmission asdescribed in U.S. Pat. No. 5,416,313. The display intensity may stillneed regulation based on the ambient light so that it is easily visibleduring the day and night without causing glare. As an example theintensity of the display may be decreased at night, and this decreasemay be signaled when the headlights are turned on.

Emissive displays which are used as EC devices in EC mirrors aretypically inorganic LEDs, fluorescent or plasma displays (e.g. see U.S.Pat. No. 5,724,187) and organic displays. As discussed below it isadvantageous to use organic displays due to their low voltage, lowpower, high efficiencies, availability in a variety of colors and lowpotential cost. Displays may also be formed inside the two surfacesconfining the electrolyte. Recently thin film displays made out oforganic materials including polymers have been commercially introduced.These displays may be activated below 20 volts, the preferred voltagefor activation in this invention is below 10 volts. This is advantageousas displays could share similar driving potentials as EC circuits,further if such displays are integrated inside the mirrors as describedbelow, they would not generate high fields. Principles of organicdisplays based on small molecules are described in Tang, C. W. et al,Applied Physics Letters, Vol 51 (1987) p-913 and those based on polymersin Friend, et al, Nature vol 347 (1990) p-539. Such displays may beassembled on the first, second, third or fourth surfaces (see FIG. 5afor definition of surface numbers). Surfaces 2 and 3 are inside thecavity between the two substrates. To keep the device thickness lowerthan the gap between the substrates, it is preferred that the device bedirectly formed on one of the substrates by depositing the active layerswhich form the display rather than assembling these devices on anothersubstrate and them bonding them to the substrates being used to form theEC devices (e.g. see U.S. Pat. No. 6,356,376). Formation of thesedevices also eases the electrical connectivity of these substrates tothe powering sources to conductive coatings rather than connectors. Theconductive coating for powering the mirror on the second or the thirdsubstrate may also be used as a conductor for this display. It ispreferred that in that case the electrode area for the display beisolated from the mirror area by creating a non-conductive deletion lineusing a laser treatment. Laser and chemical treatments to remove andpattern conductors are well known.

FIG. 7a shows an EC device where an organic display is formed on thesecond surface by a sequential deposition of layers. The EC cavity isbased on the principles of the Device in FIG. 1. 720 is the firstsubstrate which has a transparent conductive such as indium-tin oxide(ITO). This layer is etched by a fine line 722 so as to electricallyisolate an area for the display and an area to provide connectivity fromthe perimeter. Instead of etching an area, an electrically isolated areamay be created by depositing an insulating layer followed by ITO and therest of the organic light emitting stack as described below. The secondsubstrate is 710 and it has a reflective conductor 711. This is a thirdsurface mirror. As discussed earlier this could have been a window or a4^(th) surface mirror if desired. The display is formed on layer 721 bysequential deposition of several layers 762 (hole transport layer), 763(electron transport layer), 764 (cathode) and then 765. Layer 765 is anencapsulation (or a dielectric) layer which protects the underlyinglayers electrically and from the electrolyte. Since, this display iswithin the EC device it need not be sealed from oxygen or moisture, asthe main seal of the EC device protects the interior from thesematerials. If hydrophobic ionic liquids are used in the electrolyte,then the interaction of the electrolyte with any of the organic ELlayers is severely reduced. Alternatively, a protective dam may be builtaround the display so that the electrolyte does not come in contact(e.g. see U.S. Pat. No. 5,253,109) with the display. The plan view ofthe substrate 720 with the display without the encapsulation layer 765looks schematically as shown in FIG. 7b . The display area is connectedby a fine line of isolated 721, labeled as 767 to provide the power tothe display as anode. The cathode 766 similarly is isolated from 767 and721. The cathode covers the display area (see 765 in FIG. 7a ) and wrapsaround the side of the various layers and continues as 766 in FIG. 7b ).A section taken at A-A′ will resemble the view in FIG. 7a . For thosedisplays which have several segments the area 730 may be divided intosegments and then connected by several independent lines instead of asingle 767 or 766 so that it can be appropriately cabled and driven.Segmenting of displays and addressing various segments is known in theart. The pixels could be designed so that the activating layers are putdown in a passive matrix form or in an active matrix form. It ispreferred that the encapsulation layer also cover the connection area.In addition, that the encapsulant be optically diffusive and/or have anL* value in the color coordinate of less than 60 so that thereflectivity from the display area is minimized. Examples of holetransport layer are materials comprising ofN,N′-Bis(4-(2,2-naphthalen-1-yl)-N,N′-bis(phenyl)benzidene (NPB),N,N-Diphenyl-N,N-di(m-tolyl)benzidene (TPD) and poly(N-vinyl carbazole).The thickness of this layer is about 50 nm. Examples of materialscomprising electron transport layers are aluminum tris(hydroxyquinolate)(Alq₃); lithium salt of boron quinolate (LiBq₄). The thickness of thislayer is about 10 to 50 nm. Examples of cathode are calcium, aluminum,indium, magnesium, magnesium/silver alloy (e.g. 10:1 atomic ratio). Thethickness of the cathode is typically 30 to 200 nm. The dielectric layeris typically a non-conducting oxide such as silica, alumina. Thethickness of this layer is about 50 to 200 nm. The dielectric or sealinglayer may also be polymeric, e.g. parylene (Advanced Coatings, RanchoCucamonga, Calif.), epoxy, polyester, etc. All of these layers may bedeposited using physical vapor deposition (PVD) or other means. PVD ispreferred as the other areas on the substrate may be masked while thesedisplays are being formed. Dopants may be used in Alq3 layer to controlthe color of emission or increasing efficiency. For example undoped Alq3emits in green. Doping with platinum porphorion results in a redemission. Generally doped Alq3 is inserted as a separate layer betweenAlq3 and the hole transport layer. Another class of organic LEDs aremade by using polymeric materials where layers of hole injection andelectron injection are layered on top of each other. These polymers maybe spin coated or deposited from solutions using various printingtechniques such as ink-jet printing. When polymers are used, typicallythe device is similar in its layer construction as the low molecularweight organic device described above. The hole transport layer isreplaced by a hole injecting conductive polymer such as polyaniline andpoly(ethylenedioxythiophene). The electron transport layer is replacedby an electron injecting polymer layer such as poly(phenylenevinylene)(PPV) which emits in green, Cyano-PPV, polyfluorene and polythiophene.

FIG. 8 shows a device where the organic light emitting display isassembled outside the device on fourth surface. EC device is constructedon the principles of FIG. 1 with 810 and 820 being substrates coatedwith conductors on second and third surface as 821 and 811 respectively.For a third surface mirror 811 is also a reflector and a window isprovided in this reflector (not shown) to position the display. Thedisplay comprises an ITO layer 861, sequentially followed by holetransport layer 862, electron transport layer 863, cathode 864 followedby a encapsulant 865. One may even form these LEDs on a separatesubstrate, such as thin polymeric substrate and place them inside thecell by bonding to the first substrate or outside the cell bonding themto the fourth substrate. When it is placed inside the cell, thisplacement should not interfere with the electrolyte thickness for the ECdevice.

The displays may also be located outside of the mirror active area. Forexample these may be attached or built into the mirror casing, stem,etc. As an alternative, the perimeter seal may portion a corner of themirror so that this corner area is not part of the electrochromiccavity. This corner or notch is then used for a display, which may bebetween the two plates forming the EC cavity or outside. As describedabove, the display may also be formed or affixed in this area. One hasto be careful in providing too many displays and information to thedriver via the mirror, as its primary purpose is to enhance safety byproviding a clear image of the rear-view with minimum distractions.

Permanent Indicators

Permanent indicators or markings on the mirrors have been traditionallyetched, e.g., “Objects are closer than they appear on the mirror” or“Heated” on convex mirrors. Since many of these were first surfacechrome mirrors this etching was done by removing chrome. There arepatents on how these are incorporated into EC mirrors. For example U.S.Pat. Nos. 5,682,267; 5,689,370 and 5,189,537. U.S. Pat. No. 5,189,537describes that this may be formed by depositing a dielectric layer onone of the inwardly facing transparent conductors. This blocks out theEC activity in the local area, thus making the markings visible when thedevice colors. U.S. Pat. No. 5,682,267 describes that this may be doneby etching one of the interior facing surfaces before depositing thetransparent conductor. This causes the reflection change in the area ofetch. U.S. Pat. No. 5,689,370 describes another method where areflective conductor is deposited on one of the conductive surfacesfacing the interior of the EC cavity. All these methods may be used fordevices with ionic liquids.

In addition there may be other methods which could be used to impartsimilar functionality. One of these is to form this insignia on thefirst surface of the EC mirror. This is the surface outside the ECcavity exposed to the elements. The material to form this indicatorshould have a different reflectivity or color as compared to the mirrorin its various states of reflectivity. As an example this may be formedfrom chrome which may be highly reflective, diffusely reflective orcolored. To form these one may start out by using substrates which arecoated with chrome on one side and with the ITO on the other. The shapesfor the mirrors may be cut and the chrome etched, or one may etch thechrome prior to cutting the substrate or after forming the EC cavity.For bent glass coatings may optionally be done on finished shapes. Onemay also deposit chrome through a mask so that no etching is required.The deposition or 4^(th) surface reflectormay also be done byelectroless methods even after the EC cavity is fabricated before orafter filling. Other metals such as silicon, titanium, platinum, gold,nickel may also be used. One may also silk screen inks and pastesincluding frits for forming the indicators.

Another way to form this indicator is by depositing the indicatormaterial in the interior of the cavity on the second or third surfaceson top of the conductive layer similar to the process description inU.S. Pat. Nos. 5,689,370 and 5,189,537. However, unlike these patents,according to the principles of the present invention, the layer materialshould be conductive and light absorbing. In addition, this layer shouldnot promote any undesirable reactions with the electrolyte. Lightabsorbing properties to resin pastes may be imparted by adding darkcolored conductors such as carbon black or ruthenium oxide. However, asopposed to prior art one has to be careful that the base resin has arefractive index (RI) similar to one of either the layer it is depositedon or it is in contact with. For example if this layer is deposited on atransparent conductor of an EC cell formed by two substrates then theindicator material's RI should match within ±0.05 and preferably within±0.01 with ITO under photopic conditions or at 550 nm. This matchingwith contacting conductor will avoid reflectivity from the interface.The difference in the light reflected from the mirror area compared tono light coming from this area will provide high contrast for viewing.The epoxy resins and fillers which may be incorporated in them otherthan the dark conductive colorants are the same as discussed earlier forthe main seal. Various conductive carbon blacks may be purchased fromCabot Corp (Billerica, Mass.) and ruthenium oxide from ESPI (Ashland,Oreg.). These two materials may also be mixed in the resin. When theinsignia is made using conductive materials one has to be careful thatthe two opposing electrodes are not shorted. Typically their thicknessshould be less than half the cell gap (distance between the twoelectrodes or electrolyte thickness) and preferably less then 20% of thecell gap and most preferably less than 10% of the cell gap. The contentof the conductive material in the resin may range from about 2% to 25%to make the resin conductive. The processing of these, adhesionpromotion, viscosity modification by adding fumed silica is the same asdescribed earlier for main sealants. To match index with that of ITO onemay have to use materials with high aromaticity and/or halogen content.One may also use non-organic resins for this purpose. For example, thesemay be solgel formulations based on silicon and titanium precursorswhich are mixed together to yield the right RI of the matrix. The RI forITO depending on its composition and processing may vary between 1.6 to2.0. The refractive index of silica-titania solgel coatings can bevaried between 1.4 to 2.2 depending on the composition (see Chapter 14,in “Sol-gel Science” by C. J. Brinker, et. al., Academic Press, SanDiego (1990)). If these absorbing materials are put on the third surface(front surface of the rear substrate) then refractive index matchingshould be with that of the contacting electrolyte. A schematics of thisidea is shown in a single compartment EC mirror cell in FIG. 15. Afourth surface mirror device is shown made from substrates 151 and 152.which are coated with transparent conductors 154 and 153 respectively.The electrolyte 155 is enclosed by these substrates and a perimetersealant 156. The fourth surface reflector is 159. This reflector may bea multilayer coating with the side closest to the substrate beingsilver, followed by copper or its alloy and then a paint. This isstandard in mirror business where silver is protected fromelectrochemical corrosion and physical handling. The two electricalconnectors are shown by 157 and 158. The permanent indicators are shownby 153 a and 154 a. Typically only one of these is used. If 154 a isused then the refractive index of 154 a should be matched with that oftransparent conductor 154. If 153 a is used then the refractive index of153 a is matched with the electrolyte 155.

Added Feature EC Mirrors

Several of the added functionalities to the commercial automotive mirrorsystems can be preserved when using EC mirrors based on ionic liquids.For example, light sources, optical detectors and displays may beintegrated through transparent windows in the cell (e.g., see WO00/23,826). The mirror housing may have lights so as to assist thedriver at night to read instructions and maps or the exterior EC mirrorshousing may have security lights (e.g., see 00738612/EP) and integratedturn signals. The mirror assembly may have buttons and knobs for variousfunctionalities, such as to activate the mirror, change its dynamicrange, activate lights or various displays, etc., information on aspecific class of buttons can be found in U.S. Pat. No. 6,407,468.

Other additions to the mirror housings may be electronic garage dooropeners and vehicle network nodes (U.S. Pat. No. 6,396,408, US patentapplication 20020135465). Other features include microwave antennas forcommunication with external systems such as satellites or are linkedwith internal systems to display tire pressure, compass, temperature andother data (U.S. Pat. No. 6,407,712). Microphones and audio systems(U.S. Pat. No. 6,433,676) can also be attached. The audio systems mayalso be equipped with active noise control systems which cancel out theinterior car noise by actively producing out of phase sounds andcanceling the sound waves from other sources. These may also have imagesensors such as CMOS imagers (See U.S. Pat. No. 6,483,438) which may beused for anti-theft, for mirror control by detecting and analyzing glaresituations, headlight control and observing children and other occupantsin the rear of the vehicle, etc. The variable reflectivity mirrorhousing may also be used for locating Wi-fi network node so thatcompatible devices in the car or the occupants with portable devices mayaccess the internet. The interior mirror housings for EC mirrors aregenerally made of hard materials which are opaque and black in color.These housings or only the front bezels may be made with soft plasticsor coated with soft plastics to make them safer. A desired hardness ofthe surface of the cases is below Durometer 90 (A scale). Further, thecolor of the cases may be coordinated with interior colors and may beopaque or transparent. Mirrors may also be constructed where bothconnectors are on the same substrate, one such scheme is disclosed inU.S. Pat. No. 5,818,625.

Powering and Use of EC Devices and Mirrors

The EC mirrors comprising ionic liquids can be driven in similar fashionas the conventional mirrors. For example, two light sensors can bepositioned so that one is rearward facing and the other is forwardfacing. The differential, ratio or any desired function between the twocan be taken as a level of glare. Examples of such drivers can be foundin 00693397/EP and 00426503/EP A1 and U.S. Pat. No. 4,917,477. Sincevarying the voltage can control the reflectivity of these mirrors, thepowering circuits may be adapted to color them in proportion to theglare. These can also be used for headlamp control. The voltages forcoloration may be direct current which are constant with time or may bepulse width modulated to improve the response time (U.S. Pat. No.6,084,700). The controllers for these mirrors could be separate, orintegrated together. For example an image sensor described above maycapture the complete image of the rear scene and then this could beanalyzed to determine which of the mirrors (inside, outside right oroutside left) needs darkening. Glare control in U.S. Pat. No. 6,386,713,and in US patent application 20020030892 may also be used in thisinvention. The EC devices with ionic liquids can be made using variousbusbar geometries and powered using methods described in U.S. Pat. No.6,317,248. Such EC windows can also be incorporated in assemblies andcontrolled such as described in U.S. Pat. No. 6,039,390 and in WO01/84230.

Photoresistors typically use cadmium and due to environmental concernssuch resistors are an issue. Silicon based photodiodes when used aremore expensive, these do get rid of the cadmium issue but do not delivera significant jump in the performance as compared to the photoresistors.Typically the output from these is amplified using other electroniccomponents and circuitry which results in high noise. In many cases thenoise levels are so high that it is more meaningful to convert thesignals to logarithmic scales and then compare the signals from thephotosensors (e.g. see U.S. Pat. No. 5,204,778). To avoid these issuesit is preferred to use integrated sensors where the sensing and thesignal processing element are on the same silicon substrate. Suchintegration results in simplification and more miniaturization of thecircuitry while also reducing power consumption and dissipation inmirror housings. As an example, integrated light sensors may bepurchased from TAOS (Plano, Tex.). In preferred sensors, according tothe present invention, the light intensity is outputted as frequency,i.e., the output signal frequency increases with light intensity in alinear fashion. These may be programmable (e.g., TSL230R, TSL230AR,TSL230BR, TSL230RD) or non programmable such as TSL235R. Programmablemeans that the output response curve could be chosen depending on thelight input range. Further, these sensors have a high degree ofstability against changing temperature (both dark current and change inoutput) for changing light conditions. This makes them easier to installin exterior and interior mirrors, so that temperature differences willstill allow a meaningful comparison of the output of the varioussensors. Such sensors may be used in any EC mirror control scheme whichis known today, and will result in highly improved performance. Thosetemperature compensated sensors where the change in their output withtemperature is less than 500 parts per million/° C. are preferred. Thephotosensors are located in close proximity of the EC mirrors such asmirror housings or quite close such as on the mirror mount. The glaresensors may also be located so that they sense the light directly orthrough a window in the EC device. In the latter case they are able toprovide a feedback to the control system on the level of darkening.However, for the present invention either one of these locations may beused for glare sensor placement.

FIG. 9 shows a block diagram of a controller where two integratedsensors 92 and 93 are used in combination with a microcontroller 95whose timing is driven by an oscillator 96. An example of amicrocontroller is the PIC16F87x family from Microchip Technology Inc.(Chandler, Ariz.). The system is powered by the car battery (e.g., 12V,42V, etc.) through block 97 where the potential is stepped down toregulated potentials V1, V2 (typically 5Vd.c.) to feed the rest of theelectronics and a cell power line to feed block 94. VP is to providepower to the EC mirror and this may be a 9 or 12V line. The system maybe reset when the ignition switch is turned on. Block 94 comprises ofproper means of generating variable voltage for the EC cell. EC cellstypically require voltages between ±2V. For the sensors, the low noisepower supply is decoupled by a 0.01 to 0.1 microF capacitor (not shown).Two inputs of the microprocessor (I1 and I2) are used to measure thefrequency generated by the light sensors (f1 and f2). Dedicated outputs(OS) are used to select the sensitivity and full-scale output frequencyof each one of the sensors. This selection is used only if programmablesensors are used. By measuring the frequency and considering the stateof those outputs, the microcontroller determines the absolute lightintensity. Another output (OE) can control an enabling input in thesensors. Based on the intensity values, an algorithm determines thepotential to be applied to the EC mirror. This information is sent toblock 94 via a D/A (digital to analog converter) or a PWM (pulse widthmodulation signal) (OP). Block 94 produces the corresponding powersignal for the cell. If necessary, the microcontroller can also outputsignals (OSW) to close or open switches (electronic or relay type)included in block 94 to apply the voltage to the cell or evenshort-circuit it to bleach. Other outputs (OA) and inputs (IA) (digitalor analog) can control or read respectively other devices. Examples foroutput devices are headlamp-control, display-control and examples forinput are temperature, compass, rain sensor, warnings, etc. For thosecars utilizing 42V batteries, some of the voltages may be different,e.g. VP may be 42V or less.

FIG. 10 shows another control diagram that shows the use of fourintegrated sensors for a system of EC mirrors in an automobile. Thissystem has one interior mirror 1010 and two exterior mirrors 1020 and1030 respectively. The interior mirror has a display 1040 for compass.Two of the integrated sensors are located in the interior rear-viewmirror where one faces backward for glare measurement 1011 and the otherforward or placed in any other convenient position so that it measuresambient light 1012. Each of the exterior mirrors also has an integratedsensors 1021 and 1031 facing backward to measure glare. Since thesesensors have very little effect on their output with varyingtemperatures, the compensation needed for differences in temperaturewhen comparing signals from any of the glare measuring sensors and theambient sensor is not required. These sensors are temperaturecompensated over the light range of 320 to 1050 nm and from −25° C. to70° C. or −25° C. to 85° C. Compensated sensors may also be used whichcompensate in a range of less than −25° C. to over 85° C. in range.However, since the interiors and surfaces of the cars (when in motion)are usually less than 70° C., and the outside mirrors are heated, theabove ranges are sufficient. The temperature of the ambient sensorlocated in the interior of the vehicle may be quite different intemperature as compared to the one which is on the exterior of thevehicle. The other features are similar to those shown in FIG. 9. Thepower supply provides regulated voltages V1 and V2 to themicrocontroller, power to Block 1004 which comprises of proper means ofgenerating variable voltage for the EC cell and the sensors. The linesto the four sensors are not connected to keep the picture clear. 1005 isthe microcontroller and 1006 is the oscillator similar to the one inFIG. 9 for 95 and 96 respectively. The other outputs and inputs markedin microcontroller 1005 are similar in functionality as explained inFIG. 9. The interior mirror may have reading lights (not shown) and theexterior EC mirrors may have other features such as turn signals andsecurity lights. In one variation the exterior mirrors have no sensors,the interior mirror sensor controls the glare and darkens all mirrorssimultaneously when a threshold of glare is reached. In anothervariation, the sensors in the exterior mirrors are not compared to theambient sensor, rather if the glare sensors located in the individualexterior mirrors reach a certain threshold, the mirrors dim. Thus, thesemirrors may also be activated during the day. However, if one wants toavoid the mirrors from coloring during the day, their coloration mayfurther be tied to the logic generated by the internal ambient sensorwhich will keep these mirrors from activating unless the ambient lightlevels drop signaling dusk or nighttime. This signal may be generatedfrom automatic headlight sensor or from the ambient sensor describedabove. One way to generate this signal is to define a threshold levelfor the ambient sensor and/or wait when the interior rear-view mirror isactivated based on the differential interior glare and ambient sensor.One may even employ separate control system for each of the mirrorswhere each mirror has its own glare and ambient sensor. Thecommunication between interior and exterior mirrors may be wireless,such as using blue tooth technology protocols or wired.

All electronics for mirror control may be integrated in a single chip(application specific integrated circuit or ASIC). This reduces the costin high volumes. Optionally, at least one of the light sensors(preferably at least two of them which are located in the interiormirror) may also be incorporated within the same ASIC. These sensors maybe reduced in size so that their projected area may be smaller than 3 mmdiameter and preferably less than one mm in diameter, and mostpreferably less than 150 microns. This allows the sensors to be placedin the mirror area without being noticed by the car occupants. Ambientlight (from one or more locations) or glare or all of these opticallight signals may be brought to the sensor by coupling them with opticalfibers. One may also use optical comparators to compare these signals,which may also be integrated within the same ASIC. These optical signalsmay also be used for other control mechanisms in the car, for exampleautomatic headlight control. FIG. 17 shows a schematic of this concept.The figure shows an interior electrooptic mirror (e.g. an EC mirror, andmay even be an outside mirror) 176 in a housing 171. ASIC chip is 172. Afiber optic cable 175 is used for collecting the forward facing ambientlight signal via an attached lens 174. This fiber connects to the ASICvia another lens 177. Another fiber cable 179 collects a glare signalvia the lens 178. The output of this is fed to the ASIC via lens 173.The powering and other inputs to ASIC are not shown. The fiber cablesmay be fiber bundles or single filaments. One may use multiple cables tocollect the same signal for higher reliability in case the signal to oneinput gets blocked. The glare signal may also be collected through atransparent window in the electrooptic mirror. ASIC may also havecompass and temperature functionality built in which is then displayed.The ASIC may also have light emitting LEDS or displays built into them,and this information may also be optionally routed via fibers or lightguides to an appropriate place on the mirror. The ASIC may provide anumber of other options which were discussed earlier without appreciablychanging the cost of the mirror product.

According to the present invention, for mirrors, particularly forexterior mirrors that color during the daytime, a second or anadditional control-system/mechanism may be employed. One may decide tocolor them if the ambient or the exterior sensors exceed a certainintensity threshold. The mirrors may be continuously colored during dayas long as the ignition is on. During the daytime, it may not benecessary to color the mirrors to as low a reflectivity as during thenight, e.g., a photopic reflectivity of 20 to 50% may be sufficientduring the day, whereas at night a lower reflectivity may be required(e.g. less than 15% or preferably lower than 10%). Only one level may bechosen for daytime coloration, such as to mimic static blue mirrors.Since the coloring potential controls the coloration extent of the ECmirrors, a lower potential during the daytime may be chosen. Optionallymore than one level may also be chosen, where the mirrors do not coloruntil a given threshold of ambient intensity is exceeded, then color toa first level at a given threshold of ambient intensity and then colordeeper to a second level when a second intensity threshold is exceededas measured from the ambient sensor. For example, in electrochromicmirrors of the types shown in FIGS. 1-5, typically the maximum coloringvoltage, or the maximum voltage of the range of voltages used duringdaytime coloration are lower than the maximum voltage used for nighttimecoloration. For several examples discussed in this invention a voltagerange of 0.6 to 0.9V may be used for coloring during the daytime whichmay be extended to 1.4V for nighttime use. The mirrors may lowerreflectivity by coloring to any hue, but some of the preferred colorsare gray, blue-green, blue, green, blue-gray and green-gray. Further, itis preferred to have outside mirrors color to a blue color, for this thereflector may be blue in color, or one of the substrates comprising theEC cell and in front of the reflector may be tinted. The glare problemfrom the Sun typically arises at sunset and sunrise when the Sun is at ashallow angle. Since due to atmospheric scattering the Sun acquires amore yellowish/reddish hue, the blue color is able to substantiallyreduce the glare without sacrificing the vision quality, as eyes aretypically most sensitive in blue wavelength range. For daytime, only theoutside mirrors may be activated. The nighttime operation of thesemirrors may be typically done as explained above, i.e. based on theexcess difference of glare (or first glare sensor) and ambient sensor(or the first ambient sensor). For daytime operation, glare control maybe accomplished by continuous coloration as long as certain ambientlight intensity is exceeded. There may be more than one level of ambientintensity threshold accompanied by variation in coloration depth. Thisintensity threshold controlling the daytime function may be a secondcontrol mechanism which is operated only by the ambient sensor.Alternatively there may be an additional ambient sensor which controlsthe daytime function and is located on the inside or outside of the car.The second ambient sensor may be triggered only during the day by thefirst ambient sensor. The second ambient sensor may be located outsidethe car and may be optionally mounted in the exterior mirror housing andmay be optionally rear facing. This sensor may control the daytimefunction of all exterior variable reflectivity mirrors. The secondcontrol mechanism may be a manual override (e.g. by a rotary knob) wherethe auto driver may be allowed to dim the mirrors during the day to acomfortable level. This may even be tied to an auto-adjustment systemwhich is used for mirror and seat positioning for different drivers. Inthe latter case, the driver may opt to color these mirrors by a switchduring the day. This switch may then be deactivated at nighttime by theambient light sensors so that the mirrors may return to automaticcontrol. Some other features for manual control are described in U.S.Pat. No. 5,122,647 which may also be used in conjunction with thefeatures described above. Further, the depth of coloration at night mayalso be configured to this automatic adjustment system for variousdrivers, so as to take into account their sensitivity to glare. Theremay be situations where one may want to return all mirrors to aparticular state and override the automatic EC control mechanism, e.g.,one of these instances may be when the automobile is put in reversegear.

One embodiment (of the several possible) of the control mechanism wherethe daytime and the nighttime reflectivity are controlled is shown inFIG. 16. Three variable reflectivity mirrors (e.g. EC mirrors 1612, 1611and 1610) are controlled. The first two of these are exterior mirrors(e.g., right hand side mirror and the left hand side mirrorrespectively) and 1610 is an interior mirror. Also shown are threesensors, 1620 is a rearward facing sensor for glare, 1621 is a forwardfacing sensor to measure ambient light intensity, and also sensor 1622to measure ambient light intensity. Sensors 1620 and 1621 may bepreferably located in the interior mirror housing. Sensor 1622 ispreferably located in one of the exterior mirror housing. First controlMechanism is shown by box 1651 and a second control Mechanism by box1652. Sensors 1620 and 1621 feed into a subcomponent 1630 of firstMechanism. If a glare is detected, then all mirrors are darkened. Inthis simple embodiment it is assumed that all mirrors are darkened whenglare is detected by these sensors at night, although the exteriormirrors may have a different control system (not shown). The glare fromthese sensors is only detected at night because the intensity observedby sensor 1620 has to exceed that of sensor 1621. First mechanism is astandard mirror control system as described in numerous publicationsincluding those listed above. However, if no glare is detected a signalis sent to Mechanism 2 subcomponent 1640 to see if it is daytime and theambient intensity is high. This subcomponent also gets a signal responsefrom the ambient sensor 1622. If the intensity of this signal exceeds apredetermined threshold value (chosen for a particular daytime solarintensity), then the Mechanism 2 sends a signal to the exterior mirrorsto darken. The second mechanism may have several threshold valuesprogrammed to dim the mirrors accordingly to different levels.

EXAMPLES Example 1: Electrochromic Window Device Durability—UVStabilizer A

ITO substrates (15 Ω/sq) were cut into two 5.25″×3.67″ rectangularpieces. The active area of the device was about 92 sq.cm. In one piece,two holes about 3 mm in diameter were drilled near the corners of one ofthe diagonals to fill the electrolyte. The substrates were then washed,dried and stored in clean room conditions. An epoxy containing 102.5micron glass bead spacers was dispensed around the edges of one of thesubstrates and the second substrate was placed on top of it to make acavity such that the two substrates were staggered by 5 mm along thelong side of the rectangular edge. This exposed edge on both substrateswas later used to apply a busbar and make electrical connections. Theepoxy seal was cured at 150° C. The cavity was filled at roomtemperature with a liquid electrolyte containing 0.05M diethyl viologenbis(trifluoromethanesulfonyl)imide, 0.05M 5,10 dihydro-5-10-dimethylphenazine and 2 wt % of 2-4-dihydrobenzophenone (UV stabilizer) in anionic liquid. The ionic liquid was 1-butyl-3-methylpyrrolidiniumbis(trifluoromethanesulfonyl)imide (BMP). After filling, the two holeswere plugged with Teflon balls with a snug fit. The holes were furthersealed using cover glass and an epoxy. A solder strip was applied to theexposed ITO on both of the two substrates along the long sides of thecavity using an ultrasonic solder. Electrical wires were then attachedto these solder strips. The electrochromic performance of the windowdevices was determined by placing the cell in a spectrometer andfollowing the color kinetics at 550 nm while a color potential of 0.8volts was applied. The devices were bleached by shorting the twoterminals. These devices colored very uniformly to a deep blue color andreversed to the original colorless state upon bleaching. Three sets suchdevices was made, where each set had three devices. One set was cycledbetween the colored (0.8 V) and bleached state (0.0 V) at 70° C. Theresults are shown in Table 1a. Another set was exposed to UV (Society ofAutomotive Engineers J1960 test conditions) and yet another set wasstored at 85° C. and 85% relative humidity. The results are summarizedin Tables 1b and 1c respectively. The tables also show the steady statecurrent (I) in the colored state. FIGS. 11a and 11b show spectra of adevice, both in the bleached and the colored states before thecommencement of the cycling and after cycling at 70° C. for 79,500times. The spectra were taken at room temperature.

TABLE 1a Time (s) for 80% of full range I, % T (550 nm) Time to Time to(mA) Bleached Colored color bleach Initial 7.7 84.9 9.6 21.0 41.0 After79,500 7.6 84.4 9.6 21.2 41.1 cycles

TABLE 1b Time (s) for 80% of full range I, % T (550 nm) Time to Time to(mA) Bleached Colored color bleach Initial 7.9 86.1 9.4 22.2 41.7 After1,000 7.9 84.0 9.0 21.2 47.8 KJ of UV exposure

TABLE 1c Time (s) for 80% of full range I, % T (550 nm) Time to Time to(mA) Bleached Colored color bleach Initial 7.6 84.9 9.3 23.5 42.4 After720 8.4 84.5 9.1 22.9 41.5 hours@ 85° C. &85% RH

Example 2: Electrochromic Window Device Durability—UV Stabilizer B

Another set of electrochromic cells was prepared as described inExample 1. In this case, the UV stabilizer was substituted with 5 wt %of 2-cyano-3,3 diphenyl-acrylic acid ethyl ester in the same ionicliquid as Example 1. The electrochromic performance of the window devicewas determined as described in Example 1. These devices coloreduniformly to a deep blue color and reversed to the original colorlessstate upon bleaching. Three devices were subjected to each of the testsas described in example 1. The results are shown in Tables 2a, 2b and2c. The devices did not show any discoloration after any of the tests orwhen kept at −40° C.

TABLE 2a Time (s) for 80% of full range % T (550 nm) Time to Time toBleached Colored color bleach Initial 86.3 11.9 22.4 50.8 After 79,50085.9 12.1 22.6 50.1 cycles

TABLE 2b Time to 80% of full range % T (550 nm) Time to Time to BleachedColored color bleach Initial 87.1 11.1 22.9 53.9 After 1,000 KJ 81.610.2 22.9 57.5 of UV exposure

TABLE 2c Time (s) for 80% of full range % T (550 nm) Time to Time toBleached Colored color bleach Initial 93.5 12.5 23.6 52.7 After 720hours@ 85.4 11.2 21.6 46.9 85° C. &85% RH

Example 3: Electrochromic Window Device Durability—Mixed UV Stabilizers

Another set of Electrochromic windows was prepared as described inExample 1. In this case, the UV stabilizers were 2 wt % of2-4-dihydrobenzophenone and 5 wt % of 2-cyano-3,3 diphenyl-acrylic acidethyl ester in the same ionic liquid as Example 1. The electrochromicperformance of the window device was determined as described inExample 1. This device colored uniformly to a deep blue color andreversed to the original colorless state upon bleaching. Three deviceswere subjected to tests as described in Example 1. The results are shownin Tables 3a, 3b and 3c.

TABLE 3a Time (s) for 80% of full range % T (550 nm) Time to Time toBleached Colored color bleach Initial 85.1 11.1 22.2 50.3 After 79,50085.8 11.4 22.3 46.4 cycles

TABLE 3b Time (s) for 80% of full range % T (550 nm) Time to Time toBleached Colored color bleach Initial 85.8 10.8 22.3 49.2 After 1,000 kJ78.0 9.5 23.5 56.0 of UV exposure

TABLE 3c Time (s) for 80% of full range % T (550 nm) Time to Time toBleached Colored color bleach Initial 86.1 11.3 22.7 51.8 After 720hours@ 85.4 11.0 21.7 48.8 85° C. &85% RH

Example 4: Device Performance at Various Temperatures

A window device was made in a shape of an interior automotive mirrorusing two pieces of ITO coated glass. As in Example 1, these substrateswere sealed at the periphery using an epoxy. The spacing between the twoITO electrodes was 74 microns. The device was close to a trapezoidalshape with maximum length of 25 cms and width of 6.5 cms. The activearea of the device was estimated at 120 square cms. A small gap was leftin the seal for a port to introduce the electrolyte. This was backfilledat 100° C. using an electrolyte containing 0.04M diethyl viologenbis(trifluoromethanesulfonyl)imide, 0.05M 5,10 dihydro-5-10-dimethylphenazine and 5 wt % of 2-cyano-3,3 diphenyl-acrylic acid ethyl ester inan ionic liquid. The ionic liquid was BMP. The fill hole was then sealedwith a UV curing acrylate. The viscosity of this electrolyte at 25° C.was 103 cP and at 60° C. it was 23.3 cP as measured by a RheometerHBDV-III+CP (made by Brookfield, Middleboro, Mass.) using a cone andplate attachment. This device was colored by applying different coloringpotentials. The bleached state transmission of the device at 550 nm was84.3%. Its transmission at 550 nm and steady state current in thecolored state is shown in the tables below.

TABLE 4a Temperature: 25° C. Coloring potential (V) 0.7 0.8 0.9 1.0 1.11.2 T % (550 nm) 26.7 21.7 21.4 20.7 17.0 15.6 Leakage Current (mA) 7.69.5 9.5 9.5 11.7 14.0

TABLE 4b Temperature: 50° C. Coloring potential (V) 0.7 0.8 0.9 1.0 1.11.2 T % (550 nm) 40.6 29.2 23.5 22.1 21.7 21.1 Leakage Current (mA) 16.322.0 25.3 27.6 29.6 33.3

Example 5: EC Device with a Solvent Comprising Ionic Liquid and aNon-Ionic Liquid

A device was fabricated as in Example 4, but it was filled with adifferent electrolyte. The electrolyte solvent comprised of BMP ionicliquid to which 10% by weight of propylene carbonate was added. Thismixed solvent was used as a base and 0.05M diethyl viologenbis(trifluoromethanesulfonyl)imide, 0.05M 5,10 dihydro-5-10-dimethylphenazine and 5 wt % of 2-cyano-3,3 diphenyl-acrylic acid ethyl ester(UV stabilizer) was added. The viscosity of this electrolyte at 25° C.was 50.3 cP and at 60° C. 14 cP. This device was colored using differentpotentials both at 25° C. and at 50° C. The results are summarized inthe Table below. The bleached state transmission of the device at 550 nmwas 83.9%. All other details are same as in example 4.

TABLE 5a Temperature: 25° C. Coloring potential (V) 0.7 0.8 0.9 1.0 1.11.2 T % (550 nm) 25.3 17.1 15.9 15.8 14.3 12.8 Leakage Current (mA) 20.025.5 26.4 26.9 28.7 31.5

TABLE 5b Temperature: 50° C. Coloring potential (V) 0.7 0.8 0.9 1.0 1.11.2 T % (550 nm) 40.2 28.5 20.8 17.7 17.2 16.7 Leakage Current (mA) 38.454.0 66.0 70.3 71.5 74.7

Example 6: Inertness of Ionic Liquids Towards Plastics

Two common plastics were chosen, polymethylmethacrylate and flexiblepolyvinyl chloride (PVC). Three solvents were also chosen. The firstsolvent was an ionic liquid (BMP), second was propylene carbonate (PC)and the third was a mixture of BMP and PC in a proportion of 60:40 byvolume. A drop of each liquid was put on each of the three plastics. Thedrop containing PC only solubilized and damaged the area leaving whitestain where it was positioned on PMMA. The other two solventcompositions had no effect. In PVC, the PC drop was solubilized, and theother two solvent compositions maintained their shapes. The testduration was 72 hours. In another test a car dashboard was tested. Thematerial for the dashboard is not known. Drops of the three solventswere put in three different areas. The droplet with only PC left a holeabout 1 mm deep in the dashboard material after about 2 hours. The othersolvents were wiped clean and no damage was seen as examined visually.

Example 7: Third Surface Reflector EC Mirror

A mirror was made using a third surface reflector. The size of theactive area was 13.3 cm×13.3 cm. This size was chosen to roughly mimicthe size of an exterior automotive mirror. The cavity thickness was 63microns and the rear-electrode was a substrate coated with a silverlayer which was further overcoated with ITO. The conductivity of therear-electrode was 0.3 ohms/square. The front was 49 ohms/square ITO andslightly bigger than the bottom electrode to accommodate clip busbars. Aclip busbar was applied almost all around the perimeter of ITOsubstrate, excepting the two diagonal corners where the ITO coatedsubstrate was cut in order to make contacts with the rear electrode. Theelectrolyte was 70% ionic liquid (BMP) and 30% propylene carbonate (byvolume) along with a bridged dye in a concentration of 0.05 molar. Thedye was Fc-Vio imide. The mirror was colored by applying 1.2V, where themetallized electrode was held at negative polarity. The mirror wascompletely colored in approximately six seconds at room temperature. Thesteady state current in the colored state was approximately 50 mA.

Example 8: Epoxy Formulation with Long Pot Life

Several epoxy formulations were made to evaluate their Tg after curing.An epoxy formulation (formulation 1) was made using EPON™ 8281 andAncamine™ 2441. The weight ratio was 100:20. This formulation had a potlife exceeding 4 weeks at room temperature. When this was cured in adifferential scanning calorimeter and re-evaluated its Tg was 92° C. SeeExample 11 for details of Tg determination. Another formulation(formulation 2) was made where THPE-GE (a trifunctional epoxy) was addedto EPON™ 8281, and cured with Ancamine™ 2441. The weight ratio of thethree components was 20:100:24.5. This formulation had a pot life atroom temperature in excess of 7 days, as the test for pot life wasterminated after this period. The Tg of this formulation was 116° C.after it was cured in the DSC. When EPON™ 8281 was completelysubstituted by EPON 160 in formulation 2, with THPE-GE/EPON™160/Ancamine™ ratio of 20:100:26.2, the Tg under similar conditions was127° C. and had good working viscosity in excess of 11 days.

Example 9: Epoxy Formulation with Long Pot Life

An epoxy perimeter seal formulation of an electrochromic cell wasprepared from the following reagents:

TABLE 6 Material Quantity Used Shell EPON Resin 10.0 g SU-3.0 THPE/GE2.04 g HHMPA 9.207 g MY-H 0.5 g Fumed Silica 1.0 g Carbon Black 0.12 gSilicate filler 25 g Titania powder 2.4 g Glass spacers 0.1 g

The epoxy was prepared by mixing at 50° C. the EPON resin and THPE/GEuntil a complete mixture was formed. The anhydride HHMPA(Hexahydro-4-methylphthalic anhydride) was added and thoroughly mixed.The mixture was allowed to reach room temperature before the catalystMY-H was added and thoroughly mixed. The fumed silica (product 38-126-8from Aldrich Chemical Co, Milwaukee, Wis.) carbon black (Mogul L fromCabot Corp (Billerica, Mass.), epoxy silanized silicate (Novacite™ L207Afrom Malvern Industries (Hot Springs, Ark.)) titania (R960 from DupontChemicals, Wilmington, Del.) were then added under vigorous stirring.Once a homogeneous mixture was formed glass spacer beads (from Potterindustries, Canby, Oreg.) were then added under stirring. The finalmixture was a light gray color. A sample was smeared on a glasssubstrate and cured at 150° C. for one hour and its color coordinatesmeasured using an Ultra Scan XE Colorimeter (Hunterlab, Reston, Va.) inthe reflection mode. The L* a* and b* color coordinates wererespectively 43.90, −0.53 and −1.31. The uncured epoxy was stored atroom temperature under dry conditions and after more than 2 monthsshowed no change in its viscosity, and the test was terminated afterthis period. The glass transition temperature (Tg) of the epoxy wasdetermined using a Differential Scanning calorimeter (DSC) undernitrogen atmosphere at a heating rate of 10° C./minute between thetemperature range 45° C. to 200° C. For a sample cured while heating inthe DSC to 200° C. at 10° C./minute, the Tg was 131° C. and when curedin the oven at 150° C. for one hour the Tg appeared to be greater than150° C. This formulation was also cured in a microwave oven (2.45 GHz,600 W). After 5 minutes in the microwave oven (sample size about 2 g) itwas found that the resin cured to about 27% as determined by theresidual exotherm analysis when compared with uncured resin from DSCmeasurements.

Electrochromic interior mirror cells were prepared using this epoxy asthe perimeter seal. The spacer size was 88 microns. Before dispensingthe epoxy, the perimeter was primed using a primer prepared by 5 vol. %water+2 vol. % aminoethylaminopropyltrimethoxysilane (Z6020 from DowCorning MI) in ethyl alcohol. This primer was then allowed to dry underambient conditions. The epoxy was degassed prior to use. The cells werefilled with an electrolyte by back filling under argon through a fillhole left in the perimeter epoxy seal. After filling, the fill hole wassealed with an UV curing acrylate. The durability of the sealing processwas tested in an autoclave under conditions as described earlier. Theautoclave was vented every day and the cells examined. After 9 days inthe autoclave the cells were completely intact with no seal failure andcolored upon powering. The autoclave test was terminated after thisperiod. An epoxy silane glycidoxypropyltriethoxysilane (Z6040 from DowCorning) was mixed with 0.1143 g of acidified water (pH 2, by addinghydrochloric acid) for hydrolysis. Hydrolysis was done at 60° C. for 3hours under continuous stirring. For each 100 g of the above epoxyformulation, 1.2 g of this mixture was added and then this was used toprepare an EC cell without the priming step as described above. After 7days in autoclave the cells were intact. Good adhesion was also obtainedwhen non-hydrolyzed epoxy silane was added to the epoxy in the sameproportion as discussed above and passed the seven day autoclave test.After 14 days in autoclave, the cell with pre-hydrolyzed silane wasstill intact and the test was discontinued. These epoxies withnon-hydrolyzed and pre-hydrolyzed silane had shelf life of more than 3months, and they also maintained their adhesive characteristics in thisperiod.

Example 10: Epoxy Formulation with Long Pot Life

An epoxy sealant for electrochromic cells was prepared (see materialdetails in Example 9) in the concentrations shown in the table below.

TABLE 7 EPON Fumed Carbon Glass SU 3.0 THPE/GE HHMPA MY H silica BlackSilicate titania spacers 10.068 g 1.994 g 8.99 g 0.5014 g 3.0 g 0.12 g10 g 2.404 g 0.1 g

The ingredients were mixed as described in Example 9. The epoxyformulation was a light gray color and when stored at room temperaturein dry conditions showed no change in viscosity after 24 days. DSCanalysis of the epoxy showed a Tg of 122° C. (sample cured during DSCanalysis) and 144° C. for the epoxy cured in the oven at 150° C. for 1hour. Two electrochromic mirror cells were prepared as described inExample 9 using this epoxy as the perimeter seal. The epoxy was degassedprior to use. The cells was filled with an electrolyte by back fillingunder argon with the fill hole sealed with an UV curing acrylate. Thedurability of the sealing process was tested in an autoclave. After 7days in the autoclave the cells were complete intact with no sealfailure and the test was terminated.

Example 11: Epoxy with Nano-Sized Clays

An epoxy seal for an electrochromic device was prepared using a surfacemodified nano-sized clay (Nanomer 1.28E from Nanocor Inc.) as a filler.The epoxy was prepared using the following materials:

TABLE 8 EPON SU 3.0 THPE/GE HHMPA MY H Nano-sized clay 10.091 g 2.08 g9.04 g 0.5 g 3.07 g

The materials were mixed thoroughly to give a thick viscous paste. Theglass transition temperature (Tg) of the epoxy was determined using aDifferential Scanning calorimeter (DSC) under nitrogen atmosphere at aheating rate of 10° C./minute between the temperature range 45° C. to200° C. For a sample cured while heating in the DSC the Tg was 151° C.and when cured in the oven at 150° C. for one hour the Tg was 142° C.Alumina spacers manufactured by RSA Le Rubis Magasin Poudres (France)where added (0.027 g) to 2.458 g of the epoxy to form a sealant for acell application. FIG. 12 shows a DSC trace for the oven cured sample.The graph shows the change in heat flow vs. temperature. The glasstransition (Tg) area is that part of the curve where a step change isseen in the curve. The onset of Tg is calculated by extrapolating theDSC curve from before the transition and then drawing a tanget from thestep region where the curve is rising and shows the maximum slope. ΔCpis the change in specific heat at the transition or the height of thestep, and the Tg is being referred to that temperature where the changein Cp is half of ΔCp in this stepped region.

Example 12: Epoxy with Nano-Sized Clays

An epoxy sealant was prepared as described in example 5 except an EpoxyNovolac resin from Dow Chemical (D.E.N 438) was used instead of mixedEPON SU3.0 and THPE/GE as described in Example 11. The epoxy wasprepared using the following materials:

TABLE 9 D.E.N 438 HHMPA MY H Nanocor 9.98 g 7.014 g 0.5 g 3.05 g

The materials were mixed thoroughly to give a thick viscous paste. DSCanalysis was performed as described in Example 9 and for the DSC curedmaterial the Tg was 147° C. with an onset at 143° C. The material curedin an oven at 150° C. for one hour had a Tg of 146° C.

Another perimeter main seal epoxy was prepared with an inorganic contentof 28.5 wt % as follows. An inorganic of nanometer size powder NanomerI.28E from Nanocor Inc. IL was dried by heating in a vacuum oven at 100°C. for 16 hours. Immediately after drying 20 g of this material wasadded to 200 g of EPON 8281 and rapidly stirred at 120° C. for 24 hours.This formed a base resin 174-B. This base resin was formulated into asealing material according to Table 10. Ingredients such as titania andsilicate are described in Example 9.

TABLE 10 Material 174- PN Carbon Glass B 23 Titania silicate BlackSpacers Weight 10.001 2.273 1.1315 2.273 0.005 0.09 grams

A sample of the epoxy was cured in an oven for one hour at 150° C. Theoven temperature was ramped from room temperature to 150° C. at 10°C./minute. This was analyzed for Tg using a Differential Scanningcalorimeter under nitrogen atmosphere at a heating rate of 10° C./minutebetween 50° C. and 200° C. The epoxy had a Tg of 142.4° C. with an onsettemperature of 136.1° C. In the uncured state the epoxy was leftstanding 18 days under ambient laboratory conditions and showed nochange in physical appearance and was as dispensable as when freshlyprepared.

Another epoxy formulation was prepared with the following composition:

TABLE 11 Material 174- PN Carbon Glass B THPE/GE 23 Titania silicateBlack Spacers Weight 10.08 1.82 2.782 1.1315 2.272 0.005 0.09 grams

Resin 174-B and THPE/GE was premixed at 50° C., cooled and then theother additives were added as described above. When this formulation wascured in an oven at 150° C. as given above its Tg was 148° C. with anonset of 142° C. In the uncured state the epoxy was left standing 18days under ambient laboratory conditions and showed no change inphysical appearance and was dispensable as when freshly prepared.

Another formulation was made with the composition given below:

TABLE 12 Material Nano EPON PN sized Carbon 8281 40 clay silicate BlackTitania Spacers Weight 10.04 2.5 0.505 5.02 0.12 2.505 0.1 grams

EPON 8281 and nano sized clay was first mixed together before adding theother ingredients. The Tg of this material when cured in an oven at 150°C. was 134° C. and the onset was 126° C. The pot life of this materialwas in excess of 30 days.

Example 13: Characteristics of Solid Electrolyte

A liquid electrochromic electrolyte was prepared from a 70:30 wt:wt %1-butyl-3-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide andpropylene carbonate with 0.065M Fc-Vio imide. Fc-Vio imide is a dyewhich has an anodic moiety (ferrocene) which is covalently linked to acathodic moiety (viologen cation) and the anion is imide. This liquidwas solidified by adding 7.2 wt % (based on liquid electrolyte weight)of Solef 21216/1001 copolymer. The mixture was heated to 100° C. toenhance solubility and when it was cooled to room temperature a solidmaterial was obtained. Through the use of a Differential Scanningcalorimeter under nitrogen atmosphere at a heating rate of 10° C./minutethe melting onset was 64° C. with a peak temperature at 74° C. Theviscosity of the electrolyte was measured using a Brookfield DigitalRheometer with a cone and plate attachment. The trend in viscosity (FIG.13) was similar where it increased rapidly below 70° C. and could not bemeasured at 50° C.

Example 14: Solid Electrolyte in Cell

Two pieces of 40 Ω/sq. ITO coated on glass were cut into 2″×2.5″sections. One piece was drilled with two fill holes at opposite corners(of the diagonal). Cells were made by applying an epoxy containing 63micron spacers to the perimeter of one of the ITO substrates. The secondsubstrate was then placed on top of the epoxy coated ITO glass, in aposition which was staggered by 0.05 inches. Clamps were applied to theassembly at the epoxy perimeter to ensure intimate contact as well as toensure the cell spacing conformed to the spacer size in the epoxy. Thecells were fired in an oven at 150° C. for one hour to cure the epoxy.They were then filled with electrolyte under a dry inert atmosphere byinjecting the medium through one of the fill holes. Both the holes weresubsequently sealed using a Teflon ball and followed by room temperatureUV curing acrylic. A solid electrolyte was prepared as described inExample 13. The electrolyte and cell were heated to 100° C. to enablefree flow of the electrolyte into the cell cavity. Conductive metalclips with soldered leads were placed on the conductive surfaces whichprotruded from either side of the cell (along the sides which wasseparated by about 2.55 inches). These formed the electrical contacts toeach electrode. The transmission of the cell at 550 nm was 82% and underan applied potential of 1.3 volts the cell colored to 8.5%. The time tocolor 80% of this range took 16 seconds and when the leads were shortedtook 15 seconds to bleach back 80% of range. The color coordinates and %haze was measured using an Ultra Scan XE Colorimeter in the totaltransmission mode. The X, Y and Z coordinates of the cell wererespectively 73.94, 78.90 and 70.94 and haze was 0.14%. The cell did notshow any change after cycling 80,000 times at 50° C.

Example 15: Solid Electrolyte in Cells of Different Gap. Comparison withLiquid System

A solid and a liquid electrolyte were prepared as described in Example13 except that the concentration of Fc-Vio imide was 0.03M. For theliquid electrolyte the copolymer Solef 21216/1001 was not included inthe formulation. The solid electrolyte was used to fill cells asdescribed in example 14 with cell gaps of 88 and 63 μm and the liquidelectrolyte a cell with an 88 μm gap. The electrochromic properties at25° C. of the cells are shown in the following table. Leakage current issteady state current in the solid state. The cells self bleached whenthe power was removed.

TABLE 13 Time Time (sec.) (sec.) Leakage % T to Color to Bleach CurrentElec- % T (550 nm) 80% of 80% of mA/cm² trolyte Cell (550 nm) Colored atRange Range at 1.3 V Type Gap Bleached 1.3 V 1.3 V Short (25° C.) Solid88 μm 76 8 15 22 0.172 Liquid 88 μm 80 3 14 25 0.230 Solid 63 μm 78 1818 13 0.234

Example 16: Solid Electrolyte Performance as a Function Temperature

A solid electrolyte was prepared as described in Example 13. This wasused to fill a cell prepared as described in Example 14, with a cell gapof 63 μm. The electrochromic properties of the cell were measuredbetween 25° C. and −20° C. and are shown in the following table. Thecells were colored at 1.3V and bleached by shorting the two electrodes.When power was removed after coloring the cells, the cells self bleachedat all temperatures.

TABLE 14 % T Time Time % T (550 nm) (sec.) (sec.) Temp. (550 nm) Coloredto Color to Bleach ° C. Bleached at 1.3 V 80% of Range 80% of Range 2578.0 3.9 14.4 18.4 0 78.2 3.6 14.3 53.3 −10 77.5 3.7 19.9 95.4 −20 78.34.2 38.0 194.4

Example 17: Comparison of Solid and Liquid Electrolyte with Anodic andCathodic Dyes

A solid electrolyte was prepared as described in Example 14 except thatthe anodic and cathodic electrochromic dyes were diethylviologenbis(trifluoromethylsulfonyl) imide and dimethyl phenazine both atconcentrations of 0.03M. A 63 μm cell was prepared as described inexample 1 and filled with the electrolyte. At 550 nm the transmission ofthe cell was 83% and when colored at 1.3V the transmission was 34%. Tocolor and bleach 80% of range it took 6 seconds for both, when coloredat 1.3V and was shorted for bleaching. The cell had a haze value of0.09%. A similar cell was prepared with a liquid electrolyte without thepolymer. The cell had a transmission of 85% and when colored (at 1.3V)35%. To color (at 1.3V) 80% of this range took 7 seconds and 5 second tobleach. The cell had a haze value of 0.09%.

Another solid electrolyte was prepared with the same two dyes in 0.03molar concentration (each) in propylene carbonate by mixing twopolymers. A mixture of 12 wt % Solef 21216/1001 and 2 wt % Solef11008/1001 was added to solidify the electrolyte.

Example 18: EC Cell with Solid Electrolyte

A solid electrolyte was prepared by dissolving 0.065M Fc-Vio imide and9.6 wt % Solef 11008/1001 in 70:30 v:v % 1-butyl-3-methyl-pyrrolidiniumbis(trifluoromethylsulfonyl)imide and propylene carbonate. Thiselectrolyte was used to fill a 63 μm cell as described in Example 13. At550 nm the transmission of the cell was 76% and when colored at 1.3V thetransmission was 10%. The time to color 80% of this range took 25seconds and when the leads were shorted took 14 seconds to bleach back80% of range. The cell had a haze value of 0.27%.

Example 19: EC Cell with Solid Electrolyte

An electrochromic cell was prepared as described in Example 14 exceptthat the ITO electrodes used had a sheet resistance of 13 Ω/sq and thecavity spacing was 88 μm. The cell cavity was filled with an electrolyteof composition described in Example 13. At 550 nm the cell had atransmission of 77.6% and when colored at 1.3 volts a transmission of4.5%. The time to color (at 1.3V) 80% of this range took 13 seconds andwhen the leads were shorted took 19.6 seconds to bleach back 80% ofrange. At 25° C. under a color potential of 1.3 volts the cell had aleakage current of 0.258 mA/cm².

Example 20: Third Surface Interior Mirror

A third surface mirror interior automotive mirror was prepared which wasa trapezoidal shape with the distance between the parallel sides ofabout 5 cm and the average length of the parallel sides about 25 cm. Thereflective electrode was silver overcoated with ITO on glass. Theconductivity of this reflective electrode was 0.3 ohms/square. Thefront, transparent electrode was ITO coated on glass with a conductivityof 45 ohms/square. The electrolyte thickness was 63 microns and thecomposition was as described in Example 7. The scheme of busbars forthis mirror was similar to the one described in FIG. 14, where the frontelectrode had clip busbars both on top and bottom running through mostof the length of the parallel sides. The back reflector was connected attwo points on the side with clips of lengths about 1.5 cm each. Thismirror colored from 86.7% reflectivity to 8.7% reflectivity at 550 nm ata voltage of 1.2V. The coloring time to cover 80% of this range(measured from highest reflectivity) was 3.4 seconds. The bleaching timeto cover this range from lowest reflectivity was 10.5 seconds.

Example 21: Third Surface Mirror with Solid Electrolyte

A solid electrochromic electrolyte was prepared from a 70:30 v:v %1-butyl-3-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide andpropylene carbonate with 0.065M Fc-Vio imide and 7.2 wt % of a linearcopolymer Solef 21216/1001). This electrolyte was used to fill a mirrorcell prepared as described in example 14, with a cell gap of 63 μm. Therear electrode was a silver/ITO combination as described in Example 20and the front was 45 ohms ITO. The electrolyte and cell were heated to100° C. to enable free flow of the electrolyte into the cell cavity. Thereflection of the cell at 550 nm was 83% and under an applied potentialof 1.1 volts the reflection dropped to 8.0%. The time to changereflectivity 80% of this range took 8.2 seconds and when the leads wereshorted took 13 seconds to bleach back 80% of range.

Example 22: EC Cell with a Charge Transfer Dye

A charge transfer dye (Ph-Vio) was synthesized with a structure as shownbelow:

(a) An electrolyte was prepared by mixing under nitrogen 70/30 vol:vol1-butyl-3-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide andpropylene carbonate. To this mixture was added 0.05 molar Ph-Vio. Themixture was stirred to give a clear green solution. A transparent cellwith ITO of sheet resistance 13 Ω/sq and a cell gap of 88 μm (preparedas previously described in Example 14) was filled with this electrolyte.The cell was clear in the bleached state. The electrochromiccharacteristics of the cell were determined at 550 nm using a ShimadzuUV/VIS/NIR spectrometer. The transmission of the cell as a function ofcolor potential is shown in the table below.

TABLE 15 Color Potential % Transmission (Volts) (550 nm) 0.0 84.5 0.566.3 0.6 38.0 0.7 17.6 0.8 7.8 1.0 6.0 1.1 5.0

Under a color potential of 1.1V the cell colored to 80% of its range in4.7 seconds and was then bleached after full coloration by shorting thetwo terminals. Bleaching time for 80% of the range was 13 seconds.

(b) An electrolyte was prepared from a 70:30 v:v %1-butyl-3-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide andpropylene carbonate with a mixture of 0.025M charge transfer complex dye(Ph-Vio) and 0.025M Fc-Vio imide dye. Both dyes had both cathodic andanodic moieties. The mixture was heated to 60° C. to enhance solubilityand when cooled to room temperature was a clear liquid. This electrolytewas used to fill an 88 μm cell with ITO of sheet resistance 46 Ω/sq(Cell construction and size was similar as described in Example 14). At550 nm the cell had a transmission of 83% and when colored at 1.1 voltsa low end transmission of 27%. It took 7.7 seconds to color 80% of thisrange and when shorted it took 8.6 seconds to bleach 80% of range

Another sample was made (as described in Example 14) using the sameingredients as above (as in “a”), where the electrolyte was solidifiedby adding 6 weight percent of Solef 21216/1001 polymer and the chargetransfer dye concentration was 0.06M. The sample comprised of a thirdsurface mirror with silver over-coated with ITO glass as one electrodedeposited on glass, and the other electrode being 45 ohms ITO on glass,with the conductive sides facing inwards and the spacing of 63 micronsbetween them. The cell was powered by applying one busbar to oneprotruding edge and one busbar to the other protruding edge. Theseparation between then was about 2.5 inches. The cell colored from83.6% reflectivity to 8.3% when 1.1V was applied. 80% of this range wascovered in 4.5 seconds. When the two busbars were electrically shorted,the sample bleached 80% of this range in 3.9 seconds. Two additionalsamples were made where the reflective electrode was replaced by ITOcoated glass. One of these had an electrode separation of 63 microns andthe other 88 microns (electrolyte thickness). When haze was measured onthese cells, a value of 0.06% was obtained for both of them which isalmost indistinguishable from the liquid cells. Visible haze wasmeasured using Ultrascan instrument from Hunterlabs (Reston, Va.).

The foregoing description of the invention has been presented forpurposes of illustration and description and is not intended to beexhaustive or to limit the invention to the precise form disclosed, andobviously many modifications and variations are possible in light of theabove teaching. The embodiments were chosen and described in order tobest explain the principles of the invention and its practicalapplication to thereby enable others skilled in the art to best utilizethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. It is intended that thescope of the invention be defined by the claims appended hereto.

The invention claimed is:
 1. An electrochromic assembly, comprising arear element and a transparent front element bonded together by anopaque sealant in a spaced apart relationship to define a chamber, andan electrochromic material contained in the said chamber, the saidsealant comprising an epoxy resin formulation and a curing agentselected so as to have latent curing property and, (a) glass transitiontemperature in cured state in excess of 120° C. and (b) an inorganiccontent of greater than 35% by weight.
 2. An electrochromic assembly asin claim 1, where the said sealant comprises crystalline nano-particlesof inorganic materials.
 3. An electrochromic assembly as in claim 1,where the said sealant comprises UV stabilizers.
 4. An electrochromicassembly as in claim 1, where the epoxy formulation comprises fillertaken from a group comprising carbon black, fumed silica, colorants,inorganic fillers and oxygen scavengers.
 5. An electrochromic assemblyas in claim 1, wherein the said epoxy resin is cured by an anhydridecuring agent.
 6. An electrochromic assembly as in claim 1, wherein thesaid sealant further comprises a prehydrolyzed silane.
 7. Anelectrochromic mirror assembly, comprising a rear element and atransparent front element bonded together by an epoxy sealant cured withan anhydride curing agent and containing an inorganic filler in anamount greater than 35% by weight of the sealant, wherein the said frontand the rear elements are arranged in a spaced apart relationship todefine a chamber, and an electrochromic material contained in the saidchamber, and the glass transition temperature of the cured sealant beingin excess of 120° C.
 8. An electrooptic assembly, comprising a rearelement and a transparent front element bonded together by an epoxysealant in a spaced apart relationship to define a chamber, and anelectrooptic material contained in the said chamber, the said sealantcomprising a prehydrolyzed silane.
 9. An electrooptic assembly as setforth in claim 8 where the said assembly is an electrochromic mirror.10. An electrochromic assembly, comprising a rear element and atransparent front element bonded together by a sealant in a spaced apartrelationship to define a chamber, and an electrochromic materialcontained in the said chamber, the said sealant comprising at least oneof (a) crystalline nano-particles of inorganic materials and (b)silsesquioxanes.
 11. An electrochromic mirror assembly, comprising arear element and a transparent front element bonded together by asealant in a spaced apart relationship to define a chamber, and anelectrochromic material contained in the said chamber, the said sealantcomprises (a) an epoxy resin sealant with a functionality greater than2, (b) is cured by an anhydride curing agent and (c) contains aninorganic filler in an amount at least 35% by weight.